Does anyone who now has their 8 have any stats on fuel consumption? Please state if you've got the low or the high power and whether it's an auto or manual.

Also, can someone tell me if the car comes with a trip computer i.e. mpg, external thermometer, number of miles that can be covered on the remaining amount fuel....

All advice greatly appreciated.

Try here. (http://www.rx8forum.com/showthread.php?s=&threadid=494) & welcome to the forum.

Originally posted by Lensman
Try here. (http://www.rx8forum.com/showthread.php?s=&threadid=494) & welcome to the forum.

Thanks Lensman, but that thread it's mostly full of guesstimates. I was after someone who actually has a car and been through a few tanks.

The dealers are quoting about 25mpg.

i don't mean to seem stupid, but why is the engine so seemingly inefficient? in all the literature i've read on the RX-8, Mazda and others mention how much more efficient the "Renesis" is over previous versions, and they mention how the design of the engine (no conversion of linear energy into radial energy) is better, and how the engine is lighter, fewer moving parts, etc. Everything they say makes the "truth" (19-25 mpg) seem very startling. I mean, just about any MUCH heavier V6 car with an engine with more HP gets the same or better gas mileage. Am I missing something? I love the rotary concept, and everything about it and this car makes me feel like it should be a lot more efficient than everything says it is. Just wondering if someone could share why it isn't?

Q

My first tank of gas got me 16.1 miles to the gallon. That was with a lot of idleing and ogleing everywhere I parked and 90% in town driving. So I feel relatively sure this will be my worst case scenario. Winning Blue, 6MT, GT package, constant air.
Other Questions: No on board computer to track consumption. It does have an external temp gauge and internal display.

Originally posted by RX8-U-UP
My first tank of gas got me 16.1 miles to the gallon. That was with a lot of idleing and ogleing everywhere I parked and 90% in town driving. So I feel relatively sure this will be my worst case scenario. Winning Blue, 6MT, GT package, constant air.
Other Questions: No on board computer to track consumption. It does have an external temp gauge and internal display.

Thanks RX8-U-UP. Shame about the on-board computer :-(

But still, does anyone have a few tanks worth of info??

Originally posted by RX8-U-UP
My first tank of gas got me 16.1 miles to the gallon. That was with a lot of idleing and ogleing everywhere I parked and 90% in town driving. So I feel relatively sure this will be my worst case scenario. Winning Blue, 6MT, GT package, constant air.
Other Questions: No on board computer to track consumption. It does have an external temp gauge and internal display.

Ouch, my FD gets that in the city if I stay off the boost.

Originally posted by quinxy
i don't mean to seem stupid, but why is the engine so seemingly inefficient? in all the literature i've read on the RX-8, Mazda and others mention how much more efficient the "Renesis" is over previous versions, and they mention how the design of the engine (no conversion of linear energy into radial energy) is better, and how the engine is lighter, fewer moving parts, etc. Everything they say makes the "truth" (19-25 mpg) seem very startling. I mean, just about any MUCH heavier V6 car with an engine with more HP gets the same or better gas mileage. Am I missing something? I love the rotary concept, and everything about it and this car makes me feel like it should be a lot more efficient than everything says it is. Just wondering if someone could share why it isn't?

Q
I'm not any kind of rotary expert, so maybe other people will correct me on this, but my understanding is:

1) Rotary engines are inherently less thermally efficient than piston engines of the same capacity due to the very flat shape of the combustion chamber. This gives a high ratio of surface area to volume and this allows more of the combustion energy to be conducted away as heat, rather than converted into useful work.

2) Earlier rotary engines also wasted fuel by sweeping some unburnt fuel out of the exhaust port. The side ports on the Renesis no longer allow this to happen, so Mazda is correct in saying that it has improved the fuel consumption. But it's still not great.

3) Rotaries ARE very efficient in terms of the amount of power produced for a given physical size (not displacement) and weight of engine. This makes them good engines for sports cars where you want lots of power without too much weight (to preserve handling balance) and fuel consumption is less of an issue. And then there's the smoothness, high revving nature and linear power delivery which are fun in themselves.

Rotaries eat up gas at idle.

Originally posted by ChrisW
Rotary engines are inherently less thermally efficient than piston engines of the same capacity due to the very flat shape of the combustion chamber. This gives a high ratio of surface area to volume and this allows more of the combustion energy to be conducted away as heat, rather than converted into useful work.


Why not insulate the engine to reduce heat loss?

Originally posted by 8_wannabe


Why not insulate the engine to reduce heat loss?

Because then the motor will blow up from overheating due to trapped heat. Once the gasoline is converted to heat energy, there is no way for the engine to convert it back to a usable energy source. The idea is to reduce the amount of heat produced, not trap the heat. :)

Originally posted by medcina
Because then the motor will blow up from overheating due to trapped heat. Once the gasoline is converted to heat energy, there is no way for the engine to convert it back to a usable energy source. The idea is to reduce the amount of heat produced, not trap the heat.

So I guess from a size and weight standpoint, one can say the Renesis is efficient. Creates plenty of power for its size. But from a fuel consumption perspective, it is not efficient. It creates lots of wasted energy in the form of heat resulting in lower MPG. It makes a form factor like the RX-8 possible but we pay at the gas pump. Perhaps future generations of the Renesis will improve on this.

I think it would be interesting to compare vehicles based on miles per gallon per horsepower. Or even miles per gallon per horsepower per liter. :D

Originally posted by 8_wannabe


So I guess from a size and weight standpoint, one can say the Renesis is efficient. Creates plenty of power for its size. But from a fuel consumption perspective, it is not efficient. It creates lots of wasted energy in the form of heat resulting in lower MPG. It makes a form factor like the RX-8 possible but we pay at the gas pump. Perhaps future generations of the Renesis will improve on this.
That would be my take on it. However, I think people do sometimes exagerate the fuel consumption issue. I read a one page review of an RX-8 in a British magazine a few weeks ago and they mentioned poor fuel consumption three times. A couple of weeks later they reviewed the 350Z at much greater length and never mentioned fuel consumption at all. And yet, according to official UK figures, the two cars have almost identical MPG.

Rotaries have a reputation for poor MPG, but some V6's are as bad (every Alfa Romeo V6, even the 2.5, is similar to the RX-8). Unfortunately, poor MPG is one of the few things that everyone "knows" about rotaries so it does rather get done to death in every review.

but it's true, wankel engines have poor consumption efficiency... when you're talking about a race engine, that's different (where the R26B had pretty darned okayish consumption, in context), and when you're talking about a sports car, who cares??

a wankel will never be as good as a piston engine on consumption efficiency because of the nature of the mechanics (extremely oversquare, as was mentioned before lots of surface area to volume in the combustion chamber, etc etc) inherent in the design... BUT that doesn't mean you can't drive your car to get better consumption rates than someone else: if you drive to consume as little fuel as possible you won't be doing poorly by any stretch, but if you drive it to have fun you'll be eating a lot of fuel, no matter what car you have. the RX-8 might be a little higher on both accounts when compared to something with a VQ in it, but there are many many other factors which can impact fuel efficiency.

Just filled up for the first time, 6MT 18.9 MPG with 70% city
driving and 30% highway, 270 miles on a tankfull. Engine feels
as though it is beginning to free up. Hope the mileage improves
with the next tank. Love the dead pedal footrest. It is very
comfortable while driving and did not expect this. My first car with this feature.
2nd tank 19.0 mpg
3rd tank 18.2
4th tank 17.6 higher rev's

Originally posted by Zoom49
Love the dead pedal footrest. It is very
comfortable while driving and did not expect this. My first car with this feature.
Concur about that footrest. What a delight! After 6 years driving an Odyssey minivan with nowhere to put my foot this is so welcome. One of those unsung touches that really makes driving the 8 pleasant.

im dissapointed in the fuel mileage (rx8 book claims city 20.4 and hgy 30.2 epa estimate) they werent even close with 18 and 22 on the window sticker.this is almost the same as svt cobra 390hp sc v8.the cobra has a 1000.00 gas guzzler tax.im still going to get my rx8 but i just dont see the so called 40% improvment with these numbers.i hope we can get better than this. :confused:

Originally posted by akrx8
im dissapointed in the fuel mileage (rx8 book claims city 20.4 and hgy 30.2 epa estimate) they werent even close with 18 and 22 on the window sticker.this is almost the same as svt cobra 390hp sc v8.the cobra has a 1000.00 gas guzzler tax.im still going to get my rx8 but i just dont see the so called 40% improvment with these numbers.i hope we can get better than this. :confused:

Has to be more than 22 mpg on the interstate. I managed 26 in the FD from Dallas to Baton Rouge, and that was with several bursts up to 150 or so.

my mileage is pretty shitty so far. i have 120 miles and the mileage is already down to 1/4

Well, I just got mine and it's already at close to half tank with only 100 miles! Either I have a heavy foot or the gas just seem disappear for no reason. But I'm not complaining :p But I think the 6th gear crusing on the highway would help less gas consumption.

Originally posted by wakeech
but it's true, wankel engines have poor consumption efficiency... when you're talking about a race engine, that's different (where the R26B had pretty darned okayish consumption, in context), and when you're talking about a sports car, who cares??

... but there are many many other factors which can impact fuel efficiency.

It depends a LOT on how you drive it too!

I just sold my Nissan Spec V. 2.5l, 4 cylinder. The way I normally drive I got around 18mpg to 22mpg around town. It is a SPORTS CAR, dammit!

OTOH, I did try babying it a couple of times and got around 25mpg.
So, maybe you can get better mileage if you baby a piston engine, but it is a moot point for me..

really dont understand why everyone is so hung up about the fule issue. Manufacturers, and even Gov figures are well known as being mere statistics that seldomn have real world applications. Sure, they can be relative as a means to compare, but YOU will make far more impact, and your driving style will do more to determine the actual figures than any test.

They are largely irrelevent, and in a sports car even more so. As long as YOUR car is close to others in its performance bracket, thats close enough!. Here in the UK the AA found a Volvos fuel consumption to be 44% BELOW that claimed in Gov and Manufacturer tests.

ENJOY the 8`s rotary for what it is, not for what it isnt. If fuel consumption is a BIG issue, buy a diesal!.

I don't think it should be a crime to want to have a nice car even if you do a fair bit of mileage. I do nearly 20,000 miles so every mpg counts. I drive a BMW 3 series Coupe and get on average 35mpg (UK gallons). By varying my driving style and can watch it move between 28mpg and about 40mpg, but at least the BM has an on board computer so you know what you're doing.

I want to get an idea what the 8 is capable of - obviously everyone is going to have fun with the car but I want to know what that's going to cost me, and also what's possible if you behave yourself on the motorway.

Oh, by the way - I'm from the UK where standard fuel (not the fancy stuff) costs about $1.30 per litre.

At 20mpg and 20,000miles per year that works out at about ....

$6,400 of fuel per year!!!!!

That's why I ask the question about fuel consumption...

I really don't think it's any kind of "sin" to want to know what kind of gas mileage to expect from your RX-8. Sure it's a sports car but it's also being sold as a much improved more practical rotary sports GT or whatever you want to call it. So I've come to expect more than the FD gave me. I can tell you from personal experience how tough it was too drive my 93 easy so that I didn't run through $100 or more a week in gas. It was very easy to get less than 12 mpg around town but I only saw 17 mpg once or twice and 15 mpg was the norm even when taking it easy with it. It didn't help that my FD suffered from the 3-4K mysterious light throttle stutter that many FD's had. It was tough to drive it with a light throttle.

The more I read though the more I'm thinking this car will be somewhat difficult in the typical stop and go comute traffic we have here in So Cal. I just got a call that my car is in and I have to make a decision tomorrow when I go test drive it. The lack of gas mileage data this early in it's history is really making a buying decision difficult for me. So far I've seen around 18-19 mpg confirmed which isn't all that bad really. It's the unconfirmed reports of 14-16 mpg that worry me some. Anyone out there have a fill-up that yielded 20+? Estimating by reading the gas gauge is really sort of useless. We need more tank fill-up data to know where the truth lies. Anyone willing to share their data with those of us mildly concerned?

I'm in the same boat. My wife and I have a Jeep Cherokee that gets about 17 mpg, and a Ford Diesel that gets around 18 mpg. We've been looking for a car with better mileage, and I'd hoped that we could get mileage and a fun car with the RX-8; it's a little worrisome to see reports of 16mpg in an aerodynamic 3000 pound car, when my 7500 pound truck that's shaped like a brick gets 10% more than that :)

I'll be interested to see more mileage reports as more folks get their new car..

Sam

Not sure if you are looking for a real number, or just want to bicker...

In any case, I just got 19 mpg, 50-50 city/highway, a/c running (nice and cold) 103 temp outside, 6mt, 1st tank.

Thanks JR_TX. Those are some real world numbers and not too bad really. I'm just trying to decide, after my good/bad experience with my 93 RX-7 if I can overlook the faults of the the RX-8. Every car has them of course and if the strengths outweigh the faults, that's usually when you buy. And the RX-8 has plenty of obvious strengths.

But finding out the faults is tougher when the car is so new. Like the rotary impression on the hood. I never would have thought that it could trap water....and then throw it up against the windshield. Don't know if it really matters in a rainstorm or if it would have any effect while driving. But I am looking for all the things that might come up later. I just don't want to be surprised after I've spent 34K you know. The wear rating of 140 for instance and the special tires kind of put me off a little bit too, as does the low under 3K rpm torque. But for that I'd just have to drive one. My Honda CRX-SI has a very similar power curve without the gobs of power from 7-9K RPM so it might be a non-issue. My problem is I have to say yes or no tomorrow morning at 8:30 AM...my car is here!

My mileage is still about 200 miles per tank, though next time I fill up I'll do a genuine calculation to figure mpg. So far I'm still doing all suburban driving, stopngo stuff, with only a few chances to run it steady in hiway like fashion.

200 miles per tank doesn't sound all that good. Can I assume you probably had to add 14-15 gal at 200 miles and it wansn't empty so that's only 13-14 mpg. Is that right? I don't want to jump to any conclusions because there is a lot of 18-19 mpg data coming in lately. Thanks

It was very low when I filled it, but I forgot to note how many gals it took. Within a day or two I'll fill it again and get accurate info. But 200 miles on a tankful would only be about 14mpg. But then again I've just been doing suburban driving with lots of sitting at lights.

Fred, if others are like me we got our car on Day 1 and went nuts on the nearest twisties we could find. Keeping in mind the 7K RPM break-in restrictions, I'm sure none of us were driving in a fuel efficient manner in the first day or two. This morning I filled up, set my trip odometer, and started driving in a more sane manner. It will take a day or two and I'll have more representative numbers. Maybe you can delay your purchase for that long; come up with some lame excuse to stall the dealer. some folks are saying after a few hundred miles, the MPG will settle out at a better rate; I dunno if that's true or not. I have a feeling with a mix of city/hiway driving we'll be seeing somewhere around 20 MPG.

Originally posted by ggreen29
My mileage is still about 200 miles per tank, though next time I fill up I'll do a genuine calculation to figure mpg. So far I'm still doing all suburban driving, stopngo stuff, with only a few chances to run it steady in hiway like fashion.

I hope I can eke out at least 270 miles per tank otherwise I'm going to end up filling the car up every day!:eek:

Thanks all for these number - please keep them coming.

Also, I know it has been discussed on another thread but it left me a bit confused. Can anyone tell me what number I need to multiply an American mpg to get a British mpg??? A conversion from US mpg and UK mpg to European km/l would be great also!! Oh why does it have to be so confusing.

My dealer (UK) quoted me official tested figures of 23mpg for HiPower and 25mpg for the weedy one - he claimed that was based on real life road testing and not lab tests.

2nd tank.. both refilled when the gauge was teetering the "E"... Got about 275 miles or so on each.. I'd say my journeys are about 65% city 35% highway.. A/C on Full or Med close to 100% of the time... My quick calcs say I'm getting about 18-19 MPG... which is just about what Mazda claimed..

My first opinion was, "Wow that's pretty bad!".. Mind you, I'm coming from a 9 years on a motorcycle where gas was almost a non issue.. so I think I need to adjust to added $$$ :(

Thanks 8-wannabe. I might try to "trade" with someone waiting for their car in Sept, if John Hine can do that. I'm just way too confused on this issue right now. My wife says, boy are you messed up, lol. And she's right really. But I can literally flog my crx-si and still get 28-30 mpg. Granted it's only about 108 hp but still pretty quick and still in very good condition (bought new). I can wait and be patient I hope until the dust settles and more info comes in. Those constant fill-ups of premium, if that's the case, will really be irritating. It's not just the money either but part of me (the engineer part) wants to live efficiently. Surrounded as we are in So Cal by SUV's, I refuse to become part of that group, driving a lumbering, roll-over prone, gas guzzler.

But I've had cars like a '64 gto (12 mpg) and the 93 rx-7 (12 mpg) that were screamers but not very fuel efficient. I've also had semi sports cars like the crx-si and the fiat x-19 that were lots of fun and extremely fuel efficient. So I guess I'm looking for a little of both in my next car. I enjoy experiencing new technology a lot and the Mazda RX-8 has that for sure but believe it or not the new Prius for instance will have that too in a totally different way of course. I just don't think it will satisfy my need for something that handles well and definitely not a thrilling ride like the RX-8 is. So it might be best for me to wait a bit.

Anyone out there getting their car in Sept from Hine that wants mine now? Red with red and blank leather grand touring?

One of the other considerations (I hope) is that I'm not accustomed to the gearing in the sense that with my other car I know that on this road I should be in 4th gear when cruising, but that road over there is a 5th gear road. I think with the 8 I'm driving in a gear higher than I need be when I'm cruising, and I'm just not used to 5th, let alone 6th.

To make sense of US mpg, Brits can simply multiply by 1.200
(25/US = 30/GB)

Yanks have to multiply UK MPG by 0.833
(18/GB = 15/US)

Meanwhile, most of the rest of the world uses 'litres per 100 kilometres', which differs in that the distance is fixed at 100 kilometres, and the fuel used is quoted, so higher numbers is worse - and a little less fun to work out - from L/100k to GB MPG, divide 282.5 by the litres, and 235.2 for US MPG.

(10 L/100k = 28.25 GB MPG)

(10 L/100k = 23.52 US MPG)

(I am in the enviable position of living where gas is cheap, and I even get a little discount by working for an oil company. So I don't give a rats ass about my mileage! )

Had my old Legend for eight years, it gets 24 to the Imp.gallon, 22 if I drive hard, and 26 if I take it easy. Then my insurance company mentioned that if I got one more ticket, they were refusing to renew my policy. So for the last 18 months I drive like an 80 year old nun (no offence meant if you are an 80 y.o.n.!).
The car gets 30 mpg! Who knew?

In regards to your MPG worries, I would definately not buy something that was close to my 'mental cutoff' point - if you are this worried before you buy it, how will you feel if you are swayed to buy one by some good numbers, then YOURS returns 14 MPG?
If the consumption/cost is already a worry, then defo do not do it.
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doc

Our first tank got 16.1 MPG and the second tank got 16.6 MPG. This was basically all in town cruising.

We are using the 93 octane.

Maybe the MPG will continue to improve with additional break-in time.

It's not the cost in $$ doctorr. For me it's the cost of being wasteful for my own personal thrill. Guess it's my conscience kicking in. I don't want to preach here because it's a personal decision for each of us to make. It's the same reason I cut my home's personal energy consumption by over 60%, and it was modest to begin with. It's not the money I saved, even though I did save a lot with prices out here in California.

I guess it's the engineer in me that believes devices should operate efficiently and leave a minimal impact on the world while still bringing enjoyment. So yes, you're right, it is just too close to my comfort level. Still a beautiful car in so many respects and a real achievement for Mazda. Just not the car for me right now. Good luck with yours

I would imagine that the mileage will improve after the engine is broken in some. At any rate, I tend to look at such things like this:

My RX-7, the 1979 GS model, gets 15 mpg in the city. It doesn't seem to matter if I drive like a speed demon or not. On the highway, I've seen 24 mpg, but that's fairly rare. Now if the RX-8 gets better city mileage and better highway mileage than my old 7, and has 2 1/2 times the power, I'd say that's pretty damned good.

Wouldn't you?

Just got 18.1 mpg with my first tank. Probably 70% City, 30% highway with mildly spirited driving...nothing over 6000rpm..

High-Power/93 octane

I've just got the official 'certified and final' figures from Mazda UK.

The are all of the manual cars because we don't get auo (it's a yank thing). If you've got auto it would be fair to take an extra 20% off the figures. If you drive like a madman then take another 20% off. Running in will make a difference, but not that major - nothing like your driving style would.

Figures from the Hi-Power 231ps
UK mpg US mpg 10L/100km

Urban: 17.9 14.9 15.8
Extra Urban: 31.7 26.4 8.9
Combined: 24.8 20.7 11.4

Figures from the skinny one (192ps)
same colour code

Urban: 18.7 15.6 15.1
Extra Urban: 34 28.3 8.3
Combined: 26.2 21.8 10.8

Now I want to see if the numbers are true.....

As for me.... i don't regard the engine as that inefficient - the fuel economy compared to the power output is pretty good and then every single other aspect of the car is so unbelieveable that I'm going to take the extra hit in petrol spend (and might even pop into the local convent to see if they've got any 80 year olds giving advanced driving lessons!) My friend's new 911 carerra 2 gets 15mpg urban and 16 extra urban (that's 12.5 and 13.3 for our American buddies) - that I certainely could not afford (let alone the car).

I've also just found out the the 8 wont hit UK shores until model Oct and I probably won't see mine until November or even December :-((

Ouch Danny

I've gotta side with FredB though, as an engineer I find it hard to justify the fuel consumption of the 8, now i see why mazda have been so coy about publishing their figures.

not that my mileage is really gonna make that much of a cost difference, but chosing an engine which is definitely not going to win best engine in the environmental category is a little irresponsible in this day and age.

(I know it sounds weird but I'm really tempted to make a donation to one of the carbon neutral foundations, think there's one in Aberdeen)

Originally posted by KEF
Ouch Danny

I've gotta side with FredB though, as an engineer I find it hard to justify the fuel consumption of the 8, now i see why mazda have been so coy about publishing their figures.

not that my mileage is really gonna make that much of a cost difference, but chosing an engine which is definitely not going to win best engine in the environmental category is a little irresponsible in this day and age.

(I know it sounds weird but I'm really tempted to make a donation to one of the carbon neutral foundations, think there's one in Aberdeen)

See, now yer makin' me feel bad. I basically share your sentiments and I think SUVs are indefensible in most cases: 14 MPG to buy a quart of milk just don't cut it. Yet here I am with 28 MPG easily available (many Toyotas, for example.) If I can get anything over 20 MPG I'll feel ok; if not I'll be bummed mostly from a moralistic viewpoint. Anyway, I've got the 8 now so I guess I've compromised my principles. But damn, it sure is fun to drive! :D

8-wannabe I just won't fault you. I came within a half hour of buying mine. It hurt like hell to have to call the dealer and tell him to sell it. I'm sure it's probably long gone now. I never even had a ride in one....didn't want to temp myself I guess because I would have bought....weak I guess! I know how great the car must make you feel and that's got to be worth something.

I just don't think the prius is going to have the same effect for me. I could have driven the RX-8 last week when Mazda was doing the sales thing at Hine. My salesman offered to let me take his place and I didn't. I was torn then about this as I am still. I'm at home mourning my loss! But still I had to be true to what I believe. How could I ever say anything about a SUV again? But I'm still dying to go for a ride in an RX-8. Yes I'm a recovering rotary junkie is all I can say.

My downfall was bringing my streetwise 14-yr-old son along. He knew I was having mental reservations as the salesrep went in to do the paperwork. He says, "C'mon dad, you know you'll never do this again." I felt my youth slipping away before my eyes. But he's right: This is the only time I'll buy a car this impractical. So what're they gonna put on my tombstone: "Here lies Wannabe; he drove sensible cars." Not! Even if I drive this 2-3 years, I'll get it out of my system then I can grow old gracefully. But on the other hand, when my kid's grown up and I only need a two-seater I just might find myself a nice roadster with a higher mpg rating. Then I can rant about all you young wippersnappers that don't has respect for the older generation.

edit Sorry, my grammer was messed up at the end there. I should have said: "wippersnappers that don't has no respect." ;)

You are so right, 8_wannabe! My husband and I are mid 40s, kids are both married, and we have played conservative our entire lives. We have the first 8 in this area, and this is our time to shine and our 15 minutes of fame. This car turns heads! At this point, I don't care about the fuel consumption. You only live once and you can't take it with you!

Well, if I ever find my way to Fort Walton Beach I'll look you up and we'll have a fogie-rally. With no one in the back seat. Yeee-haw!

8_wannabe.....almost did it for all the same reasons. I envy you guys and who knows....I may still make the plung and get one. That red with red and black interior was soooo sweet. I'm around your ages too, a little bit older maybe. So I don't think I'll be doing this in say 20 yrs either.

I guess I should have at least gone for my test drive....got my deposit worth. It's a refundable deposit but it would have at least allowed me to experience the RX-8. Now I'll never know, lol.

For you UK folks and anyone else willing to do the conversions here (http://www.vcacarfueldata.org.uk/search_form_basic.asp) is a useful comparison tool. It's amazing to see which cars get the same mpg as the RX-8: BMW M3 anyone? It really is in SUV and limo territory which is rather poor considering that the performance isn't THAT good.

I pity you if you deny yourself the joy of driving the car you want, just so you can take joy in feeling superior to SUV drivers.

A somewhat hollow victory.
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doc

Originally posted by Doctorr
I pity you if you deny yourself the joy of driving the car you want, just so you can take joy in feeling superior to SUV drivers.

A somewhat hollow victory.
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doc

I think you're missing the point: he isn't doing it to feel superior to SUV drivers but because the SUV is a benchmark of inefficiency and the RX-8 is approaching that benchmark. He would feel hypocritical (having derided SUV engines in the past) if he purchased a similarly efficient engine. It won't stop me buying an RX-8 but I applaud the man for sticking to his principles.

Oh come on doctorr, it's really a lot more than that. And I don't at all feel superior to them. Although I do feel that we californians are way out of control when it comes to SUV's. A lady at work just bought one (Expedition) to commute. They put the largest looking rims and tires, 23" I think. The truck gets maybe 10 mpg if she's lucky pollutes much more than most of the cars on the road today. It would destroy anyone of our cars if we were involved in an accident with her. It blocks the view of all but the largest trucks when next to other vehicles on the road. I could go into American thirst for energy and how it selfishly far outstrips any other country in the world but I won't because this isn't the place really.

I don't think I'm denying myself really, but making a decision that right for me only (not you and I didn't imply that at all) and my beliefs. Like I said in earlier posts, I understand the motivation to buy an RX-8 and NEVER put anyone down for buying one. But for me the economy is just a little bit disappointing and I expected more without the turbos, new porting, etc. In fact Mazda hinting as much early on. If time proves that the car gets low 20's (even 20) with time around town (and conservative driving) then I'll change my opinion and consider that a good compromise of economy and performance. It's still a great car just not the car of my choice for now.

Hey FredB,

I am in the same boat as you now. I am going to Hine tomorrow and tell them to sell my car :(. I have family financial obligations to take care of. Not only that the gas issue that everyone talks about scares me off a little. Just like you Fred I am currently driving a CRX and averaging ~350+ on a tank. I know gas shouldn't be the deciding factor and it's NOT for me anyways.

I would be skimming it very tightly right now as my car came in a month earlier than expected (I told Eladio to put me in the 3rd allocation which would be a mid AUG delivery, but I think he bumped me up to 2nd allocations). I was planning to pay in full (I was taught by my financial advisor to pay cars cash) but with other financial obligations right now... that would mean financing the car which would be a big no no in my books. Just finished off student loans, I would dred more monthly payments.

I may have to wait a couple more months now or even wait until a '05. So does Hine write you a check back if you cancel by phone? I plan on going in just to say bye bye to my car :( , for now that is. I will have it soon though. For those with their cars congrats!

I just told them to mail the check to me, but I'm thinking of going in tomorrow too to get the check and see if they sold mine. Crazy huh....it's a pretty cool car.

Man, I am really sorry to see you guys bail on this but I can totally understand. If I hadn't gotten my car last Thursday and I'd really be having second thoughts. But, I've got it, I'm enjoying it, so I'll choose not to worry about it.

For the record, here's my stats. I ran a half tank, topped off, and started my trip odometer. Just filled up after running 212 miles and I got 17 mpg. I'm burning 89 octane.

Offsetting factors: Driving was about 1/3 city, 1/3 freeway, 1/3 twisties (sorry, couldn't wait. I made the run to Julian today.) In the future, it'll be 50/50 city/freeway so maybe it'll improve. Secondly, ran the A/C half the time (it's pretty hot and humid these days.) My driving style will calm down soon. There's a good chance I'll get close to 20 mpg before long.

8_wannabe what part of La Jolla you from. I'm in the UCSD area a lot. Maybe I'll see you around. If you see someone giving you a Thumbs Up in a white CRX that's me. :D

I think those of you who have disparaged Mazda for its claims are being a little disingenuious.

That Mazda has increased power from @180BHP in the previous non turbo, to its new level, whilst meeting all required emissions targets, AND INCREASING fuel efficiancy states just how much they have done. remember, this engine has just won International engine of the year, AND by the biggest most unaminious margin in the awards history.

Mazda is to be applauded for making this progress, especially as they are, and have been pioneering this technology on their own, and they dont have the collective efforts that the piston engine enjoys from the worlds auto makers.

Living in the UK where we pay probably some of the highest fuel prices anywhere, i am all too sensitive to these costs

What I would say to those of you that do high mileages, or where fuel cost is an issue, IF YOU ARE ON A BUDGET, you will find more efficent cars, and if fuel cost is AN ISSUE, you would be better looking elsewhere.

However, if its smiles per miles you measure driving pleasure by, you WILL NOT find a better compromise than a Rx.

Nicely said 787B. Go into it with your eyes open and you won't be dissapointed. Every single other aspect of this car really is remarkable including the basic price (which comes with soooo much equipment). People just have to be careful not to buy it and then leave it in their garage because they can't afford to run it!!

Maybe you should all start car shaing - it carries four and all your passengers will have big smiles on your faces! I car share with two other guys and have cut the number of miles I drive to the office down from 25,000 to 15,000 per year.

Originally posted by RX8-U-UP
We have the first 8 in this area, and this is our time to shine and our 15 minutes of fame.
Sure, rub it in, why don't ya...;) :D
J/K - I'm so relieved my car did not arrive before we closed on our new house. :cool:

Edit: Back on topic...when my car arrives I'll post my numbers (derived from the amount of gas GOING IN at the pump). My daily commute is 64 miles - half HWY @75'ish, and half in town from 25-65 (hmm...velocity red...better make that 25-50!) - not counting any errand-running in town or on base.

Originally posted by Renesis08
8_wannabe what part of La Jolla you from. I'm in the UCSD area a lot. Maybe I'll see you around. If you see someone giving you a Thumbs Up in a white CRX that's me. :D

Hiya, Renesis. I'm up by Soledad Mountain Road, but I get up to LJ Village Drive pretty often. I'll keep an eye out for you. Is your 8 on the way yet?

B-Nez, I can't wait to see your car! Make sure you get us a pic. Look at it this way, you'll be the first in CV! I just wanted to make a point that at some point in your life, you just have to let your hair down!

By the way, on the milage I posted for 16.1 first tank and 16.6 second tank, the A/C was on 95% of the time, and this was all in town driving on very busy tourist roads. It took us almost 30 minutes to get a couple of miles on old Highway 98 down by the beach. We just don't get on the highway that much.

The 1st tankful which was 93 octane I got 21.4 mpg. The 2nd tankfull will be better, as it was all highway driving to our vacation destination. I presently have 285 miles on this tank with slightly less than 1/4 tankful. The gas gauge looks to be accurate based upon miles driven per 1/4 tank increments.

This is better than most SUV's running the roads, and 100% more fun.

Before taking possession of my RX-8, I compared the additional costs of having to use premium gas and lower fuel economy, which figured in my case to be $700 / year.

I believe it will be the funnest and best $ 60 / month I spend.

No regrets here.

Not too bad 8_Wannabe. I'm sure that drive to Julian was spectacular in the RX-8. 17 mpg was what I got with my 93 RX-7 under the best of conditions of combined driving. That is I took it nice and easy, light throttle shifting at 4-5K. With the slight stutter that some of the RX-7's suffered (some thought it was the transition from small injectors to large) it was difficult to drive like that and easier and smoother to give it more gas avoiding that damn irritating stutter. I noticed that the RX-8 has three sets of injectors so below 4k it might be much more fuel efficient where just the smaller injectors are employed. But above 4k is where the fun begins. I found I really could enjoy the cars handling/experience, etc without having to nail it at every stop light so most of the time I was around 15+ mpg around town.

How warm does the console area feel to you? I've heard some comments that it seems warm around the shifter area to some. The fan running after stopped really isn't an issue for me. It just lets me know that Mazda learned something from the RX-7. Most of us had to modify our cars to cause the fan to run for 10 min after stopped. It did help a lot. The new RX-8 also has larger coolant passages around the exhaust port due to the side mounting from what I've read so that should help remove the heat better. Of course not having the 100,000+ RPM turbos sanwitched in there doesn't hurt either!

I took a drive last evening and noticed that because the engine is so quiet and smooth it was really easy to do most of my driving at 5k rpm or better. As I said before, once I get used to it and do most of my cruising at 3k rpm or so, I expect the mpg should improve quite a bit.

Mr. Wannabe says he got 17mpg?

If you use the 89 octane cheap stuff, the knock sensors will cut in and retard your ignition, wasting your gas energy as heat - you will have less power, more waste heat, and the extra heat will equal even LESS power and mileage.

Why would you do that?
I hope you don't think you are saving money........
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doc

That the one thing that the RX-7 has in common with the RX-8. You just didn't realize how quick it was. It was so smooth, linear, and quiet. That is until you happened to notice that you were going 20-30 mph faster than you thought. It was so deceiving.

From the owner's manual, page 5-9:
"For normal acceleration, we recommend these shift points
1 to 2 14 mph
2 to 3 23 mph
3 to 4 29 mph
4 to 5 36 mph
5 to 6 46 mph"

Except for the first two transitions, I am going much faster when I shift (about 35/45/60 for the last three.) If you follow their recommendations, you'll be running in the 3500-4000 rpm range. So, in response to FredB's comments, yes this would probably keep you on the first (small) set of injectors and increase fuel efficiency. Like ggreen, once I get used to the car I will run closer to these recommendations.

It has been noted the car really starts to get fun around 5500 rpm and I def agree with that. At 5500 in 4th/5th gear you've got great torque/acceleration and you can rocket through any gap in traffic you might see. I might have reached 7000 once, rarely get to 6500. Folks have said (after breakin) you should redline a rotary maybe once a day to keep the engine clean. This may or may not be true, but I have trouble envisioning myself doing it (though I will try.) This car just goes nuts above 7000 so hang onto your hats.

Finally, to answer FredB's question, it gets pretty warm around the center console. Not so much the shifter, but the storage compartments are warmed, ambient air temp in the cabin is warm though I don't feel any radiant heat from the engine. Air blows from the vent slightly warmed meaning if you have the fan on you're probably gonna want the AC. Keep in mind this is in the midst of a San Diego heat wave. There are conditions where I would welcome that heat, but not just now. The shifter itself isn't particularly warm. None of this is really uncomfortable or even that extreme, but it's something you notice once your other sensor stimuli wear off. It was near the end of the second day that both my son and I (and others on this forum) commented on this. It's nothing to really sweat (haha, pun) but I wish they had taken more care with the air vent ducting so it could blow into the cabin at outside ambient temperature. It's proabably getting heated about 5 degrees, so having the fan blow directly on you doesn't really give a cooling sensation on your skin. You feel like you're being warmed by the air flow. This effectively takes away the option of using the fan without AC to help fuel economy.

Originally posted by Doctorr
Mr. Wannabe says he got 17mpg?

If you use the 89 octane cheap stuff, the knock sensors will cut in and retard your ignition, wasting your gas energy as heat - you will have less power, more waste heat, and the extra heat will equal even LESS power and mileage. Why would you do that?
I hope you don't think you are saving money.

Read my other posts on how I have been driving. Just about everyone who has posted thus far has gotten 16-17 mpg on their first tankful or two. Considering how I used that gas, I'd say I'm def on the high end of the mpg experience so far. I'll keep tracking and posting, and probably start getting into 87 octane before long. This is in accordance with the owner's manual which says, "You may use a regular unleaded fuel with Octane Rating from 87 to 90 but this will slightly reduce performance."

Rehashing many long discussions from earlier posts, I am not close to reaching maximum performance from this vehicle so losing a few percent in that regard doesn't bother me in the least. And performance is not mileage; I am aware of no studies that show higher octane = greater mpg. I just don't believe it. So, I'll keep posting here over the weeks or months with my "cheap stuff" and you keep doing so as well. Let's find out through real metrics whether the lower octane has any measureable effect. I'm willing to be the guinea pig here.

Edit A cursory web search yielded the following on a Shell Oil web page:

Q. Will I get better mileage by using gasoline with a higher octane rating?
A. Octane does not directly affect gas mileage, but it can affect your car's overall performance. The octane rating of gasoline is a measure of its ability to control conditions commonly known as "knocking" and "run-on." Start with the octane level recommended in your car's owner's manual. Move up to the next level if you experience knock or run-on.

It looks like I am the only one on the forum doing this.

Like you said we are having some muggy warm weather here. I think the same is true in my CRX and I have to use the AC all the time. There's even some hotter than normal areas in the hatch area on the CRX probably due to the exhaust system routing. Maybe when our weather patterns here get back to the normal dry conditions you can just open the vents and/or sun roof and windows and you won't even notice this. Again to compare to the RX-7, it was VERY HOT in certain areas near the turbos, even on cool days. So warm is understandable with the RX-8.

What about that octane rating. You really should be using premium if you're not and that could affect the mpg as well as the heat generated by operating with a retarded ignition timing. I don't remember but I thought premium was around 91 octane in CA or am I mistaken? Since I don't need premium I don't pay much attention to that.

I filled up my RX-8 for the first time yesterday, and I got 20.2mpg. This was with 50/50 on city and freeway. I rarely used the A/C since it's beautiful right now in the northeast. Highs in the 70's, lows in the 50's, and little humidity. I'm shifting around 4-5krpm regularly with the occasional run to 6-7krpm. I can't wait for the 600 mile mark to pass to venture up to 9000rpm.

Originally posted by Ahura
I filled up my RX-8 for the first time yesterday, and I got 20.2mpg. This was with 50/50 on city and freeway. I rarely used the A/C since it's beautiful right now in the northeast. Highs in the 70's, lows in the 50's, and little humidity. I'm shifting around 4-5krpm regularly with the occasional run to 6-7krpm. I can't wait for the 600 mile mark to pass to venture up to 9000rpm.

Awesome news, Ahura. That is the best mileage I've seen posted thus far and, not coincidently, you seem to have the most moderate driving style. You give us hope. ;)

8_wannabe. I'll just add a bit of real world experience a friend of mine had. He owns a Honda Insite and was getting around 50+ mpg but only using regular gas. I'm not sure what Honda recommends for the Insite but I think they say, like Mazda, you can use regular with reduced performance, ie retarded ignition timing. When he switched to premium his mpg increased by almost 10 mpg since the car was optimized, with it's high compression ratio, to use premium gasoline. Now I do agree that you won't increase the mpg of a car designed to use regular by using premium. In fact I think I read something that indicates you might reduce your gas mileage somewhat in that situation.

To really make your test fair, you should try a tank of premium now and then so that we can normalize your data to your driving style.

Good results Ahura! Now where did I put that deposit slip for my RX-8. Wonder if it's been sold yet!?

OK, here's the summary from this forum so far. They are mostly first and second tank results from all across the country, different driving styles, etc. YOUR RESULTS MAY VARY.

Rx-U-UP 16.1
RX-U-UP 16.6
Zoom49 18.9
Gettingan8 18.0
JR_TX 19.0
RX_NUT 18.5
RX_NUT 18.5
Rotary_It_Up 18.1
8-Wannabe 17.0
RXeightr 21.4
Ahura 20.2

Average = 18.4
Range = 16.1-21.4

The average is really an estimate because we don't have all the data here like the gals used. I just took RX-NUT's 18-19 mpg data for two tanks and duplicate his average.

But this at least gives all of us some interesting results. The 14 mpg claimed by a forum member from Japan appear to be an outlier a not a true indication of the mpg.

So do those last two guys work for Mazda? Just Kidding.....really!

The area around the shifter gets so warm because the engine is much closer than in most other cars.

Originally posted by FredB
A friend of mine...owns a Honda Insite and was getting around 50+ mpg using regular gas. I'm not sure what Honda recommends for the Insite but I think they say, like Mazda, you can use regular with reduced performance, ie retarded ignition timing. When he switched to premium his mpg increased by almost 10 mpg since the car was optimized, with it's high compression ratio, to use premium gasoline. Now I do agree that you won't increase the mpg of a car designed to use regular by using premium. In fact I think I read something that indicates you might reduce your gas mileage somewhat in that situation.


The Insight recommended fuel is regular unleaded. Since, as you say, going from regular to premium in such a car won't improve gas mileage, then there must be some other explanation. I would look at: Changes to driving style or conditions; break-in period; statistical accuracy (as in, for how long and precisely did he take measurements?) I would expect the cause for mileage improvement will be found here, not due to the change in fuel grade.

I checked with my dad on the whole octane thing. He was a mechanic in the war so he knows about this stuff. He said for me to do what they did in the war: Put in two gallons of kerosene to each three gallons of gasoline. If you still worry about the octane, dump in a few mothballs or naphtha flakes. I tried it and got a stream of grey smoke. He says this means I got it just right. I'll post a test report later.

Originally posted by 8_wannabe
I checked with my dad on the whole octane thing. He was a mechanic in the war so he knows about this stuff. He said for me to do what they did in the war: Put in two gallons of kerosene to each three gallons of gasoline. If you still worry about the octane, dump in a few mothballs or naphtha flakes. I tried it and got a stream of grey smoke. He says this means I got it just right. I'll post a test report later.

Shall I call for Roadside Assistance????

You Guys must be doing something wrong.

I got just over (30) thiry miles to the gallon on the first half tank...but then the wife said she was tired of pushing it and wanted back in the car. It dropped a bit after that.:o

Originally posted by FredB
...it's the cost of being wasteful for my own personal thrill. ...and leave a minimal impact on the world while still bringing enjoyment

You own a twin turbo RX-7 and you're concerned about your impact on the environment? :D

It's not that simple anyway. Fuel usage is up but NOx emissions from the RX-8 is going to be lower than probably even your CRX. Admittedly COx emissions are up in the rx-8, but they don't cause a big brown haze and acid rain do they? :)

-pete

Mr. Wannabe, what exactly is it you are trying to do?

You say you don't want to burn Premium (because why?)

You maintain that you are not just being cheap.......

Then you tell us you and your dad are using an old 'wartime' recipe to make your own gas? From kerosine? With an octane rating of maybe 10?

Can you let us know what your aim in all this is? I am lost......

And be very careful mixing moth-balls into your mixture, that old fable started when moth-balls were made of Naphthalene (which actually has a pretty good octane rating, but grows into crystals in your fuel system, kind of a kidney stone for your car!) They haven't been made of that for many years, and the new ones are made of para-dichloro-benzene, which will not burn, is toxic, and the EPA will lock you up if they find it in your fuel.

Otherwise, it's your car, go for it!
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doc

Originally posted by Doctorr
Mr. Wannabe, what exactly is it you are trying to do?

You say you don't want to burn Premium (because why?)

You maintain that you are not just being cheap.......

Then you tell us you and your dad are using an old 'wartime' recipe to make your own gas? From kerosine? With an octane rating of maybe 10?

Can you let us know what your aim in all this is? I am lost......

And be very careful mixing moth-balls into your mixture, that old fable started when moth-balls were made of Naphthalene (which actually has a pretty good octane rating, but grows into crystals in your fuel system, kind of a kidney stone for your car!) They haven't been made of that for many years, and the new ones are made of para-dichloro-benzene, which will not burn, is toxic, and the EPA will lock you up if they find it in your fuel.

Otherwise, it's your car, go for it!

Geez, doc... lighten up. I reeled you in hook, line and sinker with that one. You need to relax and enjoy life just a little bit more. At least boowana recognized the humor of my tongue-and-cheek post. (though my dad really did do this during gas-rationing days, the moth ball lumps might tend to clog up them new-fangled fuel injectors thangs.) ;) And with a note of seriousness underlying the whole thing, I am attempting to illustrate the futility of anecdotal information in answering a systemic question. These "my friend he..." type answers don't cut it. I want to see real data backing up any allegations that premium octane has any real benefits to this car. Thus far I haven't seen it.

rpm_pwr: I owned a 93 RX7. One of the reasons I don't have it anymore is that I could not stomach 11-12 mpg. And it wasn't the money either. The other is that after I had a local rotary specialty shop install my oversize radiator, I could not get the radiator level topped off, saw remnants of combusion in the radiator fluid, and could hear sounds during boost that said something was wrong....damaged seals. So faced with a rebuild after dumping in 5K, I bailed and sold it. I bought it in spite of researching and understanding all the shortcomings of the 3rd gen, especially the 93's.

Yes I do understand your point about NOX emissions because that's why all the major manufacturers had options on the Wankel, low NOX. They didn't see any way to meet the future strict NOX emissions standards with standard technology available at that time. I don't know how it compares to the CRX-SI but that would be interesting since it is now 13 years old and I just had it smogged and have the data. The RX-8 is probably way better given today's standards.

8_wannabe: I'll have to check with my friend with the Insight on that and how everything resolved for him. You are right about regular being the recommended gas. He was one of the first owners and was driving the same route from Santee to Sorrento Valley everyday. He's the type of guy (electrical engineer/programmer) that is very careful collecting and interpreting data.

So did you have to get a permit to burn that stuff?

Well 8_wannabe, you are the 2nd lowest mpg on my list. Of course that could be due to driving style and not all that significant until we've collected more data and somehow normalized for your driving style. That's why I suggested you try a tank of premium every now and then to compare.

And maybe you have some problems with my example since you are correct about Honda recommending regular (I checked). But be careful when you ask for data. This guy with the Insite is extremely anal and I know he has lots of data on this, being the mad scientist type that he is, lol.

I just need to recheck with him on that story because it was years ago. The point I was making is that the RX-8 was designed to use premium, even though the electronics will compensate and run with regular. But what if you're out on an extremely hot day, AC on, the car loaded with two people, humidity and altitude just right and you're hitting red line when you cause the car to detonate and loose an apex seal. Or the knock sensor just isn't fast enough under extreme conditions. There are lots of RX-7 owners out there that this has happened to even after lots of succesful miles, given the right extreme conditions. The 20 cents a gallon is cheap insurance. Why experiment with your 35K dream car? Why tempt fate?

Or how about this arguement. One of the reasons you bought the RX-8 was for its performance, handling, smooth acceleration, etc. Will you admit that running with regular has to lower the perfomance somewhat? They've got to be retarding the timing when the knock sensor senses impending pinging. And retarding the timing will at least mean lower acceleration if nothing else. Heck, most RX-8 owners probably would consider performance increases, not decreases. But it is your car and this does give all of us all something to jump up and down about.

So how many mothballs to the gallon......

8_wannabe. The 2nd quote here is the more important one. No I don't have tons of data supporting this, but you don't have any to refute it I bet. Besides we all agree with you that it's a waste to run higher octane gas than your car requires and it doesn't product more power or economy. But the last quote is logical and makes perfect sense to me. As an engineer I would certainly do extensive research if I was using this statement to design a product, but that isn't the case here. I think the RX-8 manual is just telling us that if you have to put regular in for some reason, the engine management system will compensate for that.

This one is about the PT Cruiser, Turbo. For best performance, 91-octane fuel is recommended, although the engine will run on regular with some power loss. Modern engine management systems with advanced knock-sensing capability can adjust the timing to compensate for the octane rating of the fuel.

This next one is the most important from omegamotors.com. Now I don't know much about the source but I can't really find any data that refutes this and all of this makes perfect sense and is logical:

If your car requires high-octane gasoline and you habitually use regular gas because the engine exhibits no sign of knock, you’re outsmarting yourself. Most modern, computer-controlled engines include a knock sensor that detects knock and retards the ignition timing, causing the spark plugs to fire slightly later in the cycle. This typically prevents abnormal combustion and knock, which allows vehicles specified for premium fuel to run on lower-grade gasoline if it is all that’s available. While this removes the immediate hazard, it’s a bad idea to make a habit of running a vehicle on gasoline of lower-than-recommended octane. Retarding the spark causes a richer fuel/air mixture, which decreases fuel economy, increases emissions, causes the engine to run hotter, and reduces the longevity of both the engine itself and the catalytic converter. The money you save by pumping low-grade fuel into a car that demands higher octane is lost anyway, in decreased fuel economy and possibly gradual damage.

Thanks, Fred. At least you're backing up your argument with some engineering detail. I couldn't find this quote at omegamotors.com, all I found was info on selling cars. Where exactly is it? Obviously I need to learn more about knock sensors and timing. If there's a problem with lower octane, that's where it'll be. You've at least introduced enough doubt in my mind that I'll burn premium while I research this. As I've said, it's not the money savings, it's doing something for no known good reason. So I'll keep investigating.

8_wannabe:

Here it is: http://www.omegamotors.com/enjoy/gasoline/gasoline_06.html

Yes this one sums it up pretty good I think. Even with the knock sensor on the RX-7 you couldn't get away with regular so the technology has really come a log way in 10 years. I seem to remember that the stock knock sensor was notoriously slow and that lots of people were using faster, higher quality after market knock sensors especially if they had any mods. Lots of kids just added a high flow cat-back with an improved intake without changing the fuel maps, only to blow their motors after many miles without incident.

If you run premium on the next tank then we'll have our 2nd data point for you. It's only about 12% more in cost but will let you sleep easy until you find other data to contradict conventional wisdom out there.

So do you ever get over to UTC for lunch? Would love to see your car sometime.

Yeah, yeah, you got me good......!

Geez, 'Owned' by a wannabe!

Yoink.....time to go back to my beer!
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doc

It's all that emmissions crap....anybody gut their cats yet?

Here's an update with one new data point. I'll try to update this for awhile (maybe every Monday?) if I get some new data and there is interest.

Rx-U-UP 16.1
RX-U-UP 16.6
Zoom49 18.9
Gettingan8 18.0
JR_TX 19.0
RX_NUT 18.5
RX_NUT 18.5
Rotary_It_Up 18.1
8-Wannabe 17.0
RXeightr 21.4
Ahura 20.2
JR_TX 20.8

Average = 18.6
Range = 16.1-21.4

Thanks for keeping track of this; I'm in the same boat you are. The more data points I see over 20mpg, the more tempted I am.

Sam

Yes and now if Mazda would step up to the plate and say something about that AC and heat problem, we'd all feel better. I think they will soon given enough complaints about it. Seems to be easy to resolve with insulation or maybe some sort of radiant barrier. They must have seen this in the proto stage of development because I know they typically do a lot environmental testing. It will be interesting when the dealers call Mazda to ask about this. But on a more positive note, the mpg's are looking very reasonable to me and a major improvement over the RX-7.

From the owner's manual, page 5-9:
"For normal acceleration, we recommend these shift points
1 to 2 14 mph
2 to 3 23 mph
3 to 4 29 mph
4 to 5 36 mph
5 to 6 46 mph"


Let's see, in terms of RPM that's about:
1 to 2: 3500 RPM
2 to 3: 3500 RPM
3 to 4: 3000 RPM
4 to 5: 2700 RPM
5 to 6: 2700 RPM

WTF, I wouldn't even want to cruise at 2700 RPM, let alone shift up to a higher gear. That would mean cruising in 6th gear as early as 2300 RPM (46 MPH). Based on this engine that's way too low for comfort. If that's what they used to get mileage estimates, no wonder it doesn't seem to mesh with what many people are seeing in real life.

As for me, every tank seems to be improving the mileage. Most recent was 18+.

As for comparisons with an SUV, I'm also not too happy with mileage going down near that range. But it seems to me that my mileage at the worst is still better than most SUVs at their best, and I think I can live with that.

Originally posted by norats
It's all that emmissions crap....anybody gut their cats yet?
:rolleyes: shakes head..

Just for comparisons sake from the piston world, what kind of fuel economy does an s2000 get? I've heard from Canadian owners it's about 12-13L/100km.. So that would be about 18mpg US?
If that's the case I think 18-20mpg from the Renesis considering the power output is fair. Also these cars are still breaking in, I suspect the fuel economy will improve after break in.. OR it won't since you will be able to rev to redline then. :p

Originally posted by Quick_lude

:rolleyes: shakes head..

Just for comparisons sake from the piston world, what kind of fuel economy does an s2000 get? I've heard from Canadian owners it's about 12-13L/100km.. So that would be about 18mpg US?
If that's the case I think 18-20mpg from the Renesis considering the power output is fair. Also these cars are still breaking in, I suspect the fuel economy will improve after break in.. OR it won't since you will be able to rev to redline then. :p


From the s2k forum I've seen reports of as low as 10mpg (racing)and as high as 22~24mpg tops (highway) driving grandma style

Check this out and draw your conclusions on it. Myself, I'd use premium on the 8

If your car requires high-octane gasoline and you habitually use regular gas because the engine exhibits no sign of knock, you’re outsmarting yourself. Most modern, computer-controlled engines include a knock sensor that detects knock and retards the ignition timing, causing the spark plugs to fire slightly later in the cycle. This typically prevents abnormal combustion and knock, which allows vehicles specified for premium fuel to run on lower-grade gasoline if it is all that’s available. While this removes the immediate hazard, it’s a bad idea to make a habit of running a vehicle on gasoline of lower-than-recommended octane. Retarding the spark causes a richer fuel/air mixture, which decreases fuel economy, increases emissions, causes the engine to run hotter, and reduces the longevity of both the engine itself and the catalytic converter. The money you save by pumping low-grade fuel into a car that demands higher octane is lost anyway, in decreased fuel economy and possibly gradual damage.

The S2000 can get quite impressive gas mileage when driven reasonably:


http://www.s2ki.com/forums/showthread.php?threadid=67021

http://www.s2ki.com/forums/showthread.php?threadid=92693

I just finished a 900 mile round-trip (new grandson born Saturday!) and averaged about 22 mpg on interstate (cruising 75 to 80). I haven't let the tank get too low but the first quarter tank on the gauge seems to drop fairly quickly unlike other cars I've had that seem to hang on full for quite a while before showing consumption. The 16 gallon tank should get you over 300 miles regularly on a tank with mostly highway driving.

I agree with that I didn't buy this car for its mileage - I bought it for it's handling and it is a dream. My son drives a BMW M3 and we traded rides yesterday. His acceleration (on the M3) was incredible but he was jealous of great short throw "click" on the RX-8 shifter and the steady "give me all you've got" acceleration and feel of the rotary.

The 7 1/4 hour trip (each way) was pretty comfortable (love the seats). It was at least comparable to the Nissan 240 SX I've driven for the past 8 years. I hit very, very heavy rains coming back in to Cleveland but the car didn't seem to notice at all. The wipers had a little trouble keeping up with the torrential rain but the tires stuck like glue and gave a very confident feel.

More later. Hope the mileage info helps.

neit_jnf: That a pretty good summary about using regular. I sent it to 8_wannabe yesterday (see previous page) and he's going to use premium or now.

Just had 2nd fill-up. Went 307 miles & averaged 21.77 mpg.

218.6 Miles / 14.066 Gallons = 15.54 mpg

Originally posted by rxeightr
Just had 2nd fill-up. Went 307 miles & averaged 21.77 mpg.

Way to go. What were your driving habits like during this period. City/highway, hi/low acceleration, etc.

Ok, here's a quick update from the data keeper:

Rx-U-UP 16.1
RX-U-UP 16.6
Zoom49 18.9
Gettingan8 18.0
JR_TX 19.0
RX_NUT 18.5
RX_NUT 18.5
Rotary_It_Up 18.1
8-Wannabe 17.0
RXeightr 21.4
Ahura 20.2
JR_TX 20.8
RXeightr 21.8
mx32mpsrx 15.5

Average = 18.6
Range = 15.5-21.8

Wow a new low and a new high and the average stays the same.. You two should get together. Get the lead out of that foot mx32mpsrx and have some coffee Rxeightr, lol!

Originally posted by FredB
Wow a new low and a new high and the average stays the same.. You two should get together. Get the lead out of that foot mx32mpsrx and have some coffee Rxeightr, lol!

So would one more of you drive like grandma so I can have some fun? That way, it'll all work out. Thanks, Fred, for your statistical services.

God, 21.8MPG. I just scored a flat 28MPG on the way from Baton Rouge to Houston.

I don't have a lead foot and didn't go over 5000-6000 RPM. I have to run the AC at 3 or 4 almost all the time...

I'll be filling up shortly, however currently I'm sitting as follows:

185.6 miles on the tank, and the needle reads half way between 1/2 and 1/4 tank.

I think I'm doing pretty well...it looks like I'll probably see 18 MPG. That's driving the car pretty similarly to how I'd drive my Z28 and I'm getting pretty much the same gas milage. I haven't gone over 7k RPM (and typically stay with 4-5).

Question for all you though, I'm not exactly following the shift points in the book, however I do attempt to get into 5th, 6th as much as possible, and I find myself rowing this gear box a lot more than I did in the Z28...I probably don't have to...but for now I'm trying to get use to it. I'm just wondering what you all are doing for typical gear changes. I typically shift out of 1st, 2nd, and 3rd around 4-5k, then into 5th or 6th depending on how fast I'm going...I typically try to leave it in 5th or 6th making that change somewhere at 45 MPH (as long as I'll be going that speed for a little bit).

Not many of us can (are willing) to use the shift points in the owner's manual - IMHO. Sounds like you have it about right.
I'm just now allowing myself to hit 5K (700+ miles) regularly - hit 100MPH first time this AM(okay, that's about 5075RPM).
My 2nd tank was almost exactly 21MPG. By Sunday morning, I'll be able to report on tanks 3 through 6 if not 7 or 8 through about 2000 miles.

anything can be better than my 2001 eclipse. Like i said before it was a lemon and my mpg city were supossed to be about 22 and city 30 some where around there. i was getting 12 mpg city not going over 3000 rpms on a 16.4 tank i would only get 220 miles thast city and highway togeather. so compared to the eclipse my soon to be rx8 is like a civic ( i mean by better mph not pertformance.


ps dont mind speeling i can find my glasses and my face is about 3 inches away from the screen to see.

Can confirm the '93 RX-7 numbers: 12 - 17 mpg, more on the lower end when you're in the boost. Don't drive it on the highway enough to get a good reading. I only drive it 4k miles/yr so mileage does not really matter to me:p

Now our 135hp Elantra GLS gets 29 mpg no matter how hard you beat it :D

Originally posted by rotary-tt
Can confirm the '93 RX-7 numbers: 12 - 17 mpg

so, in the end the RENESIS is better on gas...

Originally posted by wakeech


so, in the end the RENESIS is better on gas...

I don't think he drove it much on the highway, so his numbers are probobly skewed downward. Still, after all of the hype for more than 2 years, its not much (if any) of an improvement considering it has less performance and a 6th gear that is really just for fuel economy. Maybe it improved in terms of emissions? Does anyone know what the EPA Smog rating was for the RX8?

It's still too early to say for sure but I'm starting to think the RX-8 is indeed 20-30% better than the RX-7 on gas mileage.

As I remember, it only took a maybe 4 or 5 good excursions on hard boost to drive the mileage down to 12 mpg for a tank full. I you take 130% of that you get 15.6.

If driven faily normal but you still let it wind out on mostly light throttle you got around 15 mpg. 130% of that is 19.5 mpg.

Now if you really really babied it, light throttle all the time, shift around 4K and maybe 20-30% highway miles you could get around 17 mpg. 130% of that is 22.1 mpg.

All of these numbers at 130% are pretty much in line with what RX-8 owners are seeing I think. If anything I'm starting to believe that if you could do a very controlled test under similar conditions the improvement might be closer to 40%. And I'm the one of the biggest skeptics here. The data doesn't lie. Some have even passed the 24 mpg on the highway by a lot.

The RX-7 might have been capable of pretty good highway mileage (I think, but don't know for sure) if driven below 70 and not using too much AC. I know it was "rated" higher, but highway trips did not seem to improve my mileage all that much and I never saw over 17 mpg with it and I had to drive like I had an egg between my foot and the gas pedal, really!

Still, there is also a lot less performance and a 6th gear in the RX8 soley for fuel economy. More importantly, the spread between the RX and its competition in fuel economy and fuel economy in relation to performance has increased substantially.

In the first tank in my EVO, I got 26 MPG with lots (probobly excessive) of idling for warm-up and cool down. That was in mixed driving conditions. I was driving very cautiously, but if you factor in the extra weight, power, torque, agressive gearing (highway cruising over around 70 enters the boost zone of the powerband) and AWD, its not bad. Still, a sixth gear is really needed, IMHO.

Its just hard to justify the fuel economy of the RX8 based on the performance. Of course, this is not a concern for many, but for you and me it is.

I'm almost through my second tank. City driving looks to be 18.5 for me. Kinda' discouraged.
The power is great but it's really goofy driving a performance car around this town. Now I own a really fast car but a lot of time I can only go 5 mph.
Nordic Green is awsome in sunlight but I'm going to have to wash it weekly.
AC performance is a bit spotty. At speed it works great but at idle the temp. definitely drops. If you close the passenger vent, the airflow on the driver's side jumps big time. The vent controls are really well designed.
TDS

Well I finally filled up, I didn't think I could make it home without doing so and my friends wanted to go for a ride...so here's the first fill up info:

230.9 miles using 12.194 gallons.

That works out to 18.9 MPG.

Not going to complain...I'd figure that about 70% of that was highway at around 70 MPH speeds with spirited sprints from toll booths and on ramps. The other 28% was city driving and the last 2% probably spent idling or revving it a bit in neutral while my friends listened to the sweet sound of the rotary.

So far, I'm driving it very similar to how I'd drive my Z28 and getting about 2 MPG better milage with smoother and quieter accelleration...can't bitch.

I'm wondering if the fuel maps are different durring the break in period resulting in much lower than anticipated gas mileage.

17 mpg was typical of my '86 and '79 RX-7's. Might get up to 22mpg on highway. Now I've been known to have a heavy foot so your mileage may vary:D

Originally posted by daedelgt
I'm wondering if the fuel maps are different durring the break in period resulting in much lower than anticipated gas mileage.

I'm wondering too. Each of us should be doing trend analysis. I just filled up and got 15.3 mpg on a tankful of 89. My prior tank -- also 89 -- I got 17 mpg. I'm now filled with 91 and we'll see. Per my earlier post, Mazda says grade of fuel won't affect mileage but will affect performance (i.e., power.) I'll try to see if I can verify this.

Originally posted by canzoomer


It depends a LOT on how you drive it too!

I just sold my Nissan Spec V. 2.5l, 4 cylinder. The way I normally drive I got around 18mpg to 22mpg around town. It is a SPORTS CAR, dammit!

OTOH, I did try babying it a couple of times and got around 25mpg.
So, maybe you can get better mileage if you baby a piston engine, but it is a moot point for me..

I also own a 2002 Sentra Spec V. I do alot of highway driving. I have had as low as 19mpg and as high as 33.9 mpg. So, it's all about how you drive it.

I got about 200 - 250 miles on my first two tanks. This was with the manual and the air on 100% of the time. I just got back from a 95% highway trip and went 299 miles using about 13.1 gallons.

DeBug

My first tank gave me 19mpg. I am hoping to get a bit better with subsequent fill ups. It is only at the gas pump that I miss my beetle TDI -- 52mpg. I used to drive from Atlanta to Tampa and fill up the next day!!

19.5 mpg on my first tank. That will go down once the engine is past the "break-in" stage. :(

Tank between 2100 and 2400 - about 24 MPG. So my avg is probably about 22. I'll calculate exactly later.

I'm averaging about 17-18mpg, because I have a lead foot... I'm past the break-in point too :)

Fill-up #4 results:

324.5 miles on 14.122 Gal = 22.98 mpg

90% highway, no revs past 6,000 rpm

Third post down:

http://www.rx8forum.com/showthread.php?s=&threadid=7494

Vince

I should add, almost all of my driving is CITY :(

And I rev past 6k all the time :)

Hey all, figured I'd report in on the 2nd tank:

249.1 miles using 13.343 gallons = 18.7 MPG.

My first tank (from above post) was

230.9 miles using 12.194 gallons = 18.9 MPG.

I'm pretty square with the average for mixed city/highway driving. However, I've still been "showing off" the car and it sits at idle for sometimes 5 minutes at a clip so that probably doesn't help...but it probably doesn't kill the MPG either. Well, still better or equal to the Camaro with better handling and similar accellaration so I'm still in love :D.

Anyway, my average so far would be 18.8 MPG, not bad at all!

If anyone is curious, I am getting much better aquinted with the shifter and becoming more and more willing to rev this thing to 6-7k, but rarely if ever do I find I need to. Typical driving on highways is 70 MPH with 6-7k shifts up the entrance ramps. I typically keep the car in 5th or 6th gear (with a constant 45 or so MPH being the cut off) at all times during city driving. During most city driving I shift at around 4-5k, unless I feel like playing and then it's 6-7k (that's more typical of my 2nd-3rd shift).

Well, enjoy everyone! But I think we can put the arguments about MPG to rest, IMO, because honestly I'm seeing equal performance vs. MPG to the Camaro with how I drive both cars. I'm sure I COULD have pushed the Camaro harder and it would have out accellarated (by very little) the RX-8. However, I would have also been "rewarded" with worse MPG doing so. So, my opinion is, yeah we're getting V-8 MPG, but we're getting it with V-8 performance (and better handling). :D

Right at 18 on my last tank of combined driving, mostly around town and I rarely shift before 5k. Haven't taken an extended highway run yet. (I have just over 700 miles).

I must say that I have been dissapointed with the gas mileage. I reflect back on the early claims of 20% improved gas mileage and suggestions of up to 30 MPG not so long ago. This car then has definitely missed the mark as far as I am concerned when it comes to fuel economy. I should be better technically speaking.
Other than that and one small adjustment problem with the passenger door light blinking on and off occassionally, the car is perfect in avey other way.:)

A fuel tank that held three or four more gallons would be nice.. Just so the needle doesn't swing down so fast!
While at the Evolution driving school we averaged 10.x MPG and that was including driving between Seattle and Tacoma twice on the freeway.
I estimate that during the school the RX-8 got about 6 MPG!

Vince

Just refilled, the light came on and it took ten gallons to fill.

Worked out to just below 25MPG, (Imperial) 20.7 (U.S).

Mostly highway trips to work (17 miles @), so not too bad, I am presuming the computer is going to run a little rich during break-in...

Revs at 60mph are fairly high, right around 3000, (3100 at 100kph) in 6th gear.
.
.
.
doc

Originally posted by Doctorr

Revs at 60mph are fairly high, right around 3000, (3100 at 100kph) in 6th gear.
.
.
.
doc

Down the road if you ever replace the clutch or something, you should research the cost associated to getting the Automatic's 4th (5th?) gear installed. It's a little better than the standard and probaby part of the reason why the auto does a little better MPG highway.

Originally posted by FritzMan


Down the road if you ever replace the clutch or something, you should research the cost associated to getting the Automatic's 4th (5th?) gear installed. It's a little better than the standard and probaby part of the reason why the auto does a little better MPG highway.
Don't think the plantary gear system of the automatic would be very adaptable to the manual transmission...but I think you meant gear ratio, not gear :D.

I thought my first tank went at a surprising rate for 2 reasons:

1) I drove like an idiot, paying exactly no attention to any sort of gentle "break-in" philosophy...
2) The tank is smallish (I think 15.9 gallons?)

However, I now think there was a third reason: the rotary is in-fact not fuel effiecient relative to the boingers.

First tank went 240 miles with 14.26 gallons: 16.83mpg -- Lightyears better than my '79 LandCruiser with a 350... and the ride is more fun as well.

Just to add another data point, I finished my first full tank yesterday. 225.7 miles on 13.58 gallons: 16.62 mpg. This was about 50/50 city and country driving, though the rural driving was not highway cruising.

So far I've seen around 18-19 mpg confirmed which isn't all that bad really

My 1987 RX-7 has averaged 20.5 MPG over the course of its 265,000 mile history...freeway driving has accounted for about three quarters of the miles & the AC has been on about half of the time.

Keep in mind that my 13B runs on 87 octane which (as per current AAA records) sells for 6.07% less than 89 octane & 7.60% less than 91 octane so your 18.5 MPG on 89 octane is going to wind up costing you 19.87% more than my 20.5 MPG on 87 octane.

Another way of looking at it is to say that a 18.5 MPG car that requires 89 octane incurs the same fuel bill as a 17.0 MPG car that can run on 87 octane. This of course ignores the environmental consideration where the goal is to minimize the number of gallons burnt. I'm not trying to take anything away from green thinkers, I just wanted to address the $$$ issue directly.

Originally posted by RX8-U-UP
My first tank of gas got me 16.1 miles to the gallon. That was with a lot of idleing and ogleing everywhere I parked and 90% in town driving. So I feel relatively sure this will be my worst case scenario. Winning Blue, 6MT, GT package, constant air.
Other Questions: No on board computer to track consumption. It does have an external temp gauge and internal display.

I'm pretty jealous of your fuel economy. I pre-ordered the 8 in January, but decided against it and bought a Z.

My fuel economy is hovering about 17-18 mpg. I understand that I am on the throttle most of the time, but it's still disconcerting. I pay over $30 per fuel up.

If the 8 came pre-equipped with the mazdaspeed body kit and wheels, then I would have had a harder decision to make.

Enjoy your cars guys!!! Beautiful cars and a heavenly sounding engine.:)

BTW, I saw a heavily modded 3rd gen 7 that was completely gorgeous and sounded amazing. I would trade in my Z in a heartbeat for one of those monsters...there's just something about a rotary engine that's addicting...maybe it's the astronomical redlines and the scream of the engine.

My previous two tanks were:

-21.3 MPG with 90% highway driving

-19.1 MPG with 50% highway

My worst so far with a lot of 7000+RPM driving was 15.1 MPG.

Currently have 1600 miles on the odometer.

I'll keeping track of my miles and mpg down in my sig area. My first fillup:

- 170 miles and 10.408 gal = 16.3 mpg ~ 90% city

This is certainly different from my previous Civic of 28.04 mpg.

Okay, here is my first 5 tanks of gas that have gotten me 944 miles. All of my driving has been in town, slow stop and go traffic, with A/C on all the time. Each tank under the same conditions have gotten better and better gas mileage, and I really have been driving it harder since the 600 mile point. So heres the results.

1st tank 16.3
2nd tank 16.22
3rd tank 16.02
4th tank 17.32
5th tank 18.21

Like I said, I know that I am driving it harder now that I did during break-in, but it keeps getting better. Happy driving.

So my first tank gave me 19.0mpg.
My second tank gave me 18.5mpg

Yes, we are using alot of A/C and we are communting (stuck on idle here and there) but still I was hoping to be over 20 everyday and 24on highways/weekends.

I will report the first 5 tanks to give some more info.

After my first tank I only got 14.7 mpg:( I wish I could say I've been drivin it hard and perhaps this is why but I have been keeping it under 5K, 40% cty, 60% hwy. I'm hoping my next tank will be a little better.

When I first fire up my car, I warm it up for a good 5 minutes, sometimes shorter, sometimes longer depending on the temp gauge. I'm sure that whacks a lot of fuel... dont it?

Originally posted by RX-Nut
When I first fire up my car, I warm it up for a good 5 minutes, sometimes shorter, sometimes longer depending on the temp gauge. I'm sure that whacks a lot of fuel... dont it? Five minutes? Are you crazy?

No modern car needs more of a warm-up than the time it takes for you to buckle your seatbelt. Sit, start, buckle, go. If it's really cold out (say 20°F or below), perhaps give it 30 seconds, tops.

If you are letting the engine run for five minutes not only are you unnecessarily heating the emission control system but you may as well be tossing money out the window and spilling fuel destined for your tank on the ground at your next fill-up...

As far as regular economy goes, the sticker I saw at my dealer said 18 city/24 highway and most of the reports here seem pretty consistent with that...

First tank 19.85 (babyed it)
2nd 19.5 (mountian)
3rd 19.6 (lots of high reving)

Umm, no. If you run the car before it gets up to a decent temperature your just shortening the life span of the car. The oil isn't hot enough, and the seals have not expanded completely.

i'm at 750 miles or so, last tank was 16.1 mpg 91 octane from union76, getting better than the 13-14mpg i started off at =)

Originally posted by daedelgt
Umm, no. If you run the car before it gets up to a decent temperature your just shortening the life span of the car. The oil isn't hot enough, and the seals have not expanded completely. I'm not saying to redline it, but rather the best way to warm any modern engine is to drive the car. Idling is horrid for a vehicle - there is little airflow to cool the engine and none to cool the exhaust system. Letting your car idle for five minutes every morning is a good way to be on the road to a new catalytic converter early.

I picked up my 8 in Nova Scotia and live in Newfoundland - 1350km (~845 miles) from home. Immediately left the dealership and put all highway miles on it.

Fuel consumption results:
160 litres of 93 octane consumed (42.27 US gal)
1350 km travelled (all highway) (844 mi)

19.96 mpg highway - not nearly as good as I would have hoped. Any thoughts?

Originally posted by bgparsons3
19.96 mpg highway - not nearly as good as I would have hoped. Any thoughts? Just what others have mentioned - conventional piston-engined cars tend to see their MPG improve over the first 3000 miles or so. I suspect the rotary's mileage will also improve as the apex seals break in.

Originally posted by BillK
I'm not saying to redline it, but rather the best way to warm any modern engine is to drive the car. Idling is horrid for a vehicle - there is little airflow to cool the engine and none to cool the exhaust system. Letting your car idle for five minutes every morning is a good way to be on the road to a new catalytic converter early.

Oh, well 5 minutes is excessive, but a modern car is not ready to go when you have out on your seatbelt. I know my FD makes some funny noises until it gets to about 100°f, which takes at least 1-2 minutes.

For those still keeping track, just got 17.3 mpg over about a tank and a half. This makes my mpg since buying the car: 17, 15.3, 16, 17.3. At least I'm on an upward trend after an initial dip and still not driving like a grandma. I run A/C at least half the time, punch it when I want (which is pretty often), cruise at about 80 mph, and my last tankful included the Great San Diego RX-8 Rally which was a lot of twisties.

(whoa, I just figured over the last tank vice 1.5 tanks I got 18.2, so I really am feeling better now. If I start averaging 20 I can shake that SUV-morality guilt complex.) Also, for the sake of full disclosure the last 1.5 tanks was 91 octane; I just filled it with 87. We'll see. ;)

16.5 mpg on first tank. The low fuel light seems to come on with more than
2 gallons to go.
50% city vs. highway.

Originally posted by daedelgt
Oh, well 5 minutes is excessive, but a modern car is not ready to go when you have out on your seatbelt. I know my FD makes some funny noises until it gets to about 100°f, which takes at least 1-2 minutes. I wouldn't call your FD a modern car, either...

Most any new vehicle's owner's manual says warm up is not necessary, just drive gently until the car comes up to full temperature...

I got around 17.10 gallons on my second tank. It was mostly city driving, to and from work and so on.

I'm going to keep track of this 3rd tank, and see how it goes as well.

Just one other thing - the disclaimer from the bottom of the EPA mileage estimates of 18 city, 24 highway states:
Actual Mileage will vary with options, driving conditions, driving habits and vehicle's condition. Results reported to EPA indicate that the majority of vehicles with these estimates will achieve between 15 and 21 mpg in the city, and between 20 and 28 mpg on the highway.

I mentioned this in one of the dyno threads. When one member ran his car on the dyno and recorded his Air/Fuel ratio, we noticed that the car went rich in the upper half of the rev range. There is speculation that the less than advertised HP output is due to the ECU being tuned differently for the first several thousand miles or so while the engine breaks in (which would explain why dealerships are telling people to drive the car normally, just avoid hanging rpms for awhile).

I wonder if this possible protective over-rich situation is also why the fuel economy is so poor on these new engines, and it will improve once the ECU changes over to normal mode...

---jps

I'll try this one.

If you use x liters every 100 kM, your mpg is 234.7 divided by x.

This is how I calculated this number. Let's say your car uses 12 liters
every 100 kM. A liter is 33.814 ounces, and a gallon is 128 ounces, so 12
liters = 12 * 33.814 ounces = 405.77 ounces = 405.77 / 128 gallons = 3.17
gallons. A kilometer is .62 mile, so 100 kilometers = 62 miles. Thus, if
you get 12 liters every 100 kM, your mileage is 62 miles per 3.17 gallons,
or 19.56 miles per gallon.

To summarize the conversion, if you use x liters every 100 kM, your mpg is
234.7 divided by x. (This number 234.7 comes from the above logic because
it equals 62 * 128 / 33.814).

HTH

Ken Sax
nsxtasy@mcs.com
Windy City Chapter BMWCCA



Conversely, if you need MPG, just take (234.7) / L per 100km.

Sputnik, good connection... a temporary rich-fuel-map-for-break-in ECU mode would indeed tend to waste gas. To me, both the low-dyno and low-fuel-economy (relative to Mazda specs) observations/concerns that new owners are having are very interesting -- I can't wait for the truth to come out, which may be difficult to get to. If the 8s operating software truly evolves with mileage, then that seems hard to test. Hopefully Mazda will eventually explain one way or the other (i.e. YES, program behavior is catered to mileage -- or NO, all algorithms are fixed).

I bet the first company that engineers a "chip" for the 8 will realize the truth during R&D. Furthermore, it will be interesting to see what a chip will do for this naturally aspirated coffee grinder, err... RENESIS. IMO, if a chip gives it more than 10 hp, then we know that Mazda has these conservatively tuned. After all, with a "different" design, there is extra emphasis on proving reliability. Problems with a convential engine in a new car could be attributed to a production line hiccup, but with the 8s alot of people will scream "f---ing Wankel!" and then a "those things don't work" reputation will be off and runnning...

Woah, long post... sorry to waste all those bytes.

Originally posted by notdeafyet
I bet the first company that engineers a "chip" for the 8 will realize the truth during R&D. IMO, if a chip gives it more than 10 hp, then we know that Mazda has these conservatively tuned. After all, with a "different" design, there is extra emphasis on proving reliability. Problems with a convential engine in a new car could be attributed to a production line hiccup, but with the 8s alot of people will scream "f---ing Wankel!" and then a "those things don't work" reputation will be off and runnning...

I have to admit, this is all new territory to me. Notdeaf, are you saying that aftermarket manufacturers could make a replacement chip for the ECU? Is this something that commonly happens on different makes/models? If so, is it hard to install, does it void any warranties, and can you get different chips tuned to performance and/or economy? This is probably yesterday's news to y'all but to me it's a new concept. Thanks!

Tank #5 - 93 Octane:
311.4 Miles * 13.416 Gal = 23.21 mpg (best yet for me)

My type of "typical" driving: 70% highway w/ no revs above 6K

Trying my 1st tank of 91 octane now.

Originally posted by rxeightr
Tank #5 - 93 Octane:
311.4 Miles * 13.416 Gal = 23.21 mpg (best yet for me)

My type of "typical" driving: 70% highway w/ no revs above 6K

Trying my 1st tank of 91 octane now.

1st Tank averaged out to be 14mpg (total 229 miles)
2nd Tank averaged out to be 17mpg (don't recall the mileage)
Working on the 3rd tank ...

But keep in mind the car started with 4.5 miles on it and over time it seems to be getting better (not to mention the 1st tank dealt with some harder driving than the second too - hehehe)...

Most of my driving has been highway; however highway in Charlotte doesn't say a lot. Typical morning and afternoon commutes tend to include a lot of stop-and-go traffic conditions because of backed up interstates...

We're going to be taking a trip from Charlotte NC to Williamsburg VA in mid-September and we'll be driving the RX8. It'll be interesting to see how well she really does out on the open highway versus driving around town and daily work commutes.

Keep the data coming in so we can all see how we measure up !!!!! :D

I've read through about 50% of this thread. I'm not really seeing the increased mileage of the RX8. My FD gets 12mpg in town, I know that is much worse than the RX8 but I drive the hell out of it. If I stay off boost I get 15mpg in town.

On the freeway I just completed a 291 mile trip from Seattle to Eugene, mileage was 23.1mpg. Typical highway mileage is 21-23mpg.

Seems like the 8 is barely hitting that?

Originally posted by 8_wannabe
I have to admit, this is all new territory to me. Notdeaf, are you saying that aftermarket manufacturers could make a replacement chip for the ECU? Most likely.Is this something that commonly happens on different makes/models? Yes, with varying results. If so, is it hard to install... Normally, no. ...does it void any warranties... You betcha! and can you get different chips tuned to performance and/or economy? Normally, the car is already tuned for the best economy and reliability from the factory. The tuning on an NA engine normally advances timing, changes fuel maps, allows for higher rpms, etc., all in the name of performance. Normally, for a simple chip replacement, you aren't going to be able to dictate what you want.

---jps

OK, for my second tank of gasoline, I got 18.39 MPG (didn't record the first tank).

Mostly city driving, with AC on most of the time. Pretty aggressive driving (I had to respond to a VW Jetta who did a Jack rabbit start on a freeway on-ramp. I had to respond to put him in his place and uphold the RX-8 honor) so I red-lined "unintentionally" before my 600 mile break in period. Oh well, it was worth it! :D

My next tank will probably be better, as I'll probably drive a little more sanely!

Second tank for me was is 18.1 mpg

Originally posted by turbojeff
I've read through about 50% of this thread. I'm not really seeing the increased mileage of the RX8. My FD gets 12mpg in town, I know that is much worse than the RX8 but I drive the hell out of it. If I stay off boost I get 15mpg in town.

On the freeway I just completed a 291 mile trip from Seattle to Eugene, mileage was 23.1mpg. Typical highway mileage is 21-23mpg.

Seems like the 8 is barely hitting that?

Filled her up yesterday and did a check ... 7.071 gallons at 125 miles on the trip meter averages to 17.667 mpg ... Again, that's driving with a lot of idle and stop-and-go traffic. :D

Originally posted by vix8
OK, for my second tank of gasoline, I got 18.39 MPG (didn't record the first tank).

Mostly city driving, with AC on most of the time. Pretty aggressive driving (I had to respond to a VW Jetta who did a Jack rabbit start on a freeway on-ramp. I had to respond to put him in his place and uphold the RX-8 honor) so I red-lined "unintentionally" before my 600 mile break in period. Oh well, it was worth it! :D

My next tank will probably be better, as I'll probably drive a little more sanely!

Does your city driving involve a lot of stop-and-go along with idle driving?

Charlotte NC is well known for it's horrible interstate commute weekday traffic ... Imagine a 3-4 lane interstate being a parking lot from 7:15am until 9am and 4:30pm until 6:30pm ... It's terrible ..

I wouldn't even say that my daily driving really classifies as city driving to me because the car's RPMs are constantly up and down for the majority of time just due to stop and go at short distances... A lot of times shorter than a typical block.

Originally posted by MaRX8
Second tank for me was is 18.1 mpg

That sounds pretty good. At least you've broken the lower spec. I'm still trying to get there :-) ... 17.667 is the highest for me thus far...

Are you driving an AT or MT?

Well here are my first three tanks:

93 octane everytime.

19, 18.5, 18.3. I am going down for some reason. We are in Atlanta with stop and go commute and high A/C use, but still there is a fair share of highway everyday and nontraffic night driving(with no A/C). I can't get that 23 etc that others are getting.

Filled up for the second and third times yesterday, before and after a decent thrash on the countryside.

Second tank: 11.22 gallons for 200 miles of city driving - 17.8 mpg
Third tank: 10.47 gallons for 188.4 miles of high-speed highway and enthusiastic twisties - 17.99 mpg.

My first tank was identical to RX-8-u-up's - 16.1 in town. My 2001 Millennia S got 18 mpg on the same drive pattern (work) and with AC running. The other cars I looked at - 350Z, G35 were very similar to the RX and it is OK. My greatest concern is that we get the Horsepower/Performance issue resolved.

My first one isn't complete but it's HORRIBLE! Does the top half go faster? I went 150Km on 1/2tank or 30 liters!

Of course I haven't been going light on the car (not too hard) but shifting at 5K instead of 3 and shifting at 7 k a few times :D

If you think it's going do down fast the first half, it will go down even faster on the second half.

Watch how fast the miles go up. Isn't that car a blast to drive...and drive...and drive?

220 miles at first fill up, 14.1 gallons. 15.71 mpg. lots of showing off on regular roads the first weekend thru twisties and such. cruising between 4 and 6k most of the time on highways. ac on most of the time. i have heard peopel say you get better mileage with the windows closed and the ac on than with the windows open and no ac, is this true? there will be more highway miles on my next tank, so the economy should be better.

Third tank check in...Jeeeeze it's been a while since I've been to this board, too much work lately :( got to pay for the car.

Anyway, here's my 3rd tank:

255.0 miles using 13.439 gallons = 18.97 MPG.

And for good justice, here's a re-cap of my 1st and 2nd:

1st: 230.9 miles using 12.194 gallons = 18.9 MPG.
2nd: 249.1 miles using 13.343 gallons = 18.7 MPG.

The best part is that the 3rd tank was ALL "city" (not really stop and go city, but not constant speeds on the highway). Plus this tank I've been bouncing above 6k a lot more frequently and have hit 7-8k a couple times here and there.

I think some of you guys doing really badly are just either always shifting a 7-8, or holding RPMS above 3k for much longer than you need to. I find that just about every gear shift around 3-4k will bring you down around 2-2.5k. If you are going to be at a certain speed for more than a couple lights, you may consider downshifting at around 3-4k to stay below 3k (where the 2nd injectors pop open) if at all possible.

Anyway, happy driving everyone!! I think I'll continue keeping track of this for a bit...just for my own edification. Although, it's funny, every time I look at the gas gauge and then start to fill up I think, damn I've driving this thing harder this time, I think my MPG is going to be shit, and then the pump stops at around the same gallon mark as the previous tank, but I've gone just a lil' bit further. :D, break in is almost over (I'm at around 750 miles), so then I'll see what the real story is once I start unleashing the power a bit more. But as I've said many times, I'm doing better than I did in my Z28 with similar driving, so I'm happy.