By the way, the service tech also told me: stay away from gas with methyl-ethyl alcohol. As he put it, this is just a "filler" that sucks down your gas mileage. He says Chevron and Shell do NOT use these so they should give better results. I usually buy gas on the Navy base (Navy exchange); don't know if they use these fillers or not. Does it say on the pump? Will it say how much they've added? And, is it true what this guy is saying? I've seen people on this forum say Shell and Chevron are better, but they cited different reasons (additives like Techroline.) I never believed these wive's tales, but the alcohol theory sounds plausible. Can any of our hydrocarbon experts weigh in with knowledgable info on this (not opinions, guesswork, or "my brother he" stories.)

You should ask them to hook up the computer then YOU drive it around all week. I'm not positive but it shouldn't take a Mazda tech to just drive around....

What a concept, 8. If their computer is really logging the right metrics they'll be able to see how I'm driving. Plus, after owning this for 5 weeks I trust myself better to drive serenely than some techie who's got his one chance to "see what it'll do." The only setback is, I won't be able to do this till after my trip. Add time for corrective actions on their part, if any. Leaves me a couple weeks to decide about keeping the car or not. They told me I need to decide by Oct 1 on the turn-in deal.

BTW, lest I be flamed, the 9 hp problem is completely inconsequential to me. But if I knew the 8 would get such poor mileage I never would have bought it. It's expensive and socially unconscienable in my book. The fact that I'm getting a second chance to return the car is just serendipitous as far as I'm concerned. There is no other "problem" with the 8 that makes me unhappy enough to return it since the "fun factor" outweighs everything else. However, if I gotta drive like grandma the car is no longer fun and that's a big problem for me. If I can get at least 20 mpg by trying, and less when having fun, that's good enough. Right now, I'm not even close.

This mileage stuff is insane. Do you all suppose it's going to get better with break in? I would also say the "9hp problem" is more like a 30hp problem. But youare right, as long as the car is fun to drive that's what matters most.

Gas mileage HAS NOT improved after break-in.. I'm getting the same.. actually have adjusted my driving, so I'm still getting about 215 to a tank, but only filling up once a week so It's normal for me now I guess.. hopefully something will get fixed to change this.. so instead of me driving a car with 247hp and getting 13mpg, I'm driving a 180 hp car and STILL getting 13mpg! Where's the justice?! I love it tho :)

yup 8_wannabe - count me in.

Just went through another tank & you guessed it - 13.6 MPG. :(

I called John Hine, here in SD where I bough the car and spoke w/ a service guy about the mileage. He was implying that the Califonia 8s have more emissions & are heavier than other states. I thought they just built them all to meet California emissions??? Sounds like flim-flam to me. Anyone can comment on this?

Re: Re: 18mpg on 4th tank
 

Funny how this is the only car I have ever owned that I needed a bunch of know-it-alls on a forum telling me how to drive to obtain EPA MPG. I never really gave it much thought how different I drive this car than the 25 others I've owned. I usually use A/C if it's hot, I drive over the speed limit sometimes, I roll my windows up and down depending on the weather, sometimes I shift in the power band, sometimes I don't...blah blah blah.

Guess I ain't smart enuff to own this perdy lil sports car. Guess I'll have to opt for the buy-back and look for a dumber car that's easier to drive properly.

Did I say I love this car? ;)

astrlsrfr,

You definately seem to have a car with MPG problems.

I curious to know if you have one of the earlier allocation of cars or a low VIN#. I started a thread Does specific VIN#'s = problematic cars? to see if we can collect data on whether owners that problems correlate to a specific VIN range, etc.

In regards to your emissions question... I believe you are right. I seem to recall reading that all the RX-8's are the same emissions standard. There is not two different "emission versions".

Re: Re: Re: 18mpg on 4th tank
 

The Renesis is probably just more sensitive to driving behavior than many other engines are. This type of thing happens all the time with various vehicles and it's just the way the EPA testing process works.

People have been saying the EPA numbers are wrong or are impossible to achieve; they're not. EPA numbers are often difficult to reproduce, and I suspect the fact that the RX-8 is a sporty car makes it doubly difficult to reproduce because people tend to drive it harder than they would a Camry.

When I owned an Audi TT, I remember some people on the TT board complaining about the gas mileage they were seeing. It turned out that for many "normal" driving involved high RPMs and turbo use. I never used my turbo except on a highway on-ramp and often shifted around 3K and would regularly almost get EPA highway numbers midway between city and highway in mixed driving. Likewise I've rode with friends in their cars and have asked them why they were beating the crap out of their engines by revving them to 5K or 6K before shifting. They laughed and told me "it's a car, it's meant to be driven" and later would tell me about their sub-par gas mileage.

So, IMHO, are the EPA numbers "lies" or "unachievable"? No. Are they for some people's driving styles? Perhaps...

Re: Re: Re: Re: 18mpg on 4th tank
 

I would like to believe this, however it seems no matter what I do to my car (baby it or flail it) I get around 16-something mpg. Other folks have said no matter what they, they get around 21. Obviously, you can't flair it for 200 miles and expect that, but my point is there seems to be two variants of the car: Hi-mileage ones and low-mileage ones. It's weird...

Everyone keeps talking about "how to drive" the car, where and when to shift, redline vs. no redline. But nobody is mentioning the main cause of poor gas mileage - speed. Since acceleration lasts for only a few seconds, whether you shift at redline, or at 3000 rpm, that will only slightly impact your gas mileage. Cruise speed will influence gas mileage MUCH more, since that is where the majority of driving occurs.

If you cruise at 85 mph, you're going to get crappy gas mileage compared to cruising at 60 mph; no matter what car you drive. So, you have a choice, do you want to drive fast, or do you want to get good gas mileage? If you want to drive fast, then deal with the lower gas mileage. If you want good gas mileage -- SLOW DOWN!

End of rant. :)

Only partially right, and even then an oversimplification. First, acceleration makes a huge impact, particularly for city and short-term freeway driving (as in, when you can't just set cruise and off you go.) Secondly, it's engine speed not necessarily roadspeed that'll kill you. I could drive 60 and get crummy mileage. Why? Because I'm in third gear. Same road speed, same wind resistance, different engine speed. In 6th gear at 3000 rpm you're going maybe 65 or so; that oughta be about optimal economy. I could comment further on your post, but I should more properly put it under the Flaming Jerks thread.

Edit: Done. If you want to discuss low mileage of the car, please post here. If you want to discuss my ancestry or other non-sequitors please go the to Flaming Jerks thread.

I routinely get 13.5 MPG using an RX-8 delivered in Richmond, VA.

How many miles you got on the car now? I just topped 2000. My mileage was down in the 15's, now I've gotten 17.5 mpg the last two fillups. I shift routinely at 3000 rpm but still have a heavy foot on the freeway. I use regular (87 octane), just filled up with Shell as I was told they (and Chevron) don't add methyl ethyl alcohol, which reduces mileage. I don't know if that story is true but I'm determined to solve this mystery by the end of sept when I have to decide whether to keep the car.

Just passed 1,100. I was averaging 13.5 so this last tank I was very careful to shift at 4,500 RPM or lower, get it into 6th (or 5th) ASAP and to do minimal downshifting. That got me some very dull driving and roughly 15 MPG. Who says driving habits don't change gas mileage :) .

I use premium but I will have to check if the methyl ethyl alcohol is an additive routinely used in VA.

I got concerned about other, comparably powered cars getting better gas mileage. I spent an afternoon researching on the Internet and discovered all the other cars get their performance from higher engine torque and lower rear-axle ratios. The RX-8 4.444 ratio is a killer for gas mileage. Even in 6th, the effective ratio is still higher that the 350z, which is heavier and has more power but gets better gas mileage.

OTOH, we might just be being rewarded for getting early (mid July) delivery.

there are a lot of imponderables and unknowns in this equation, but two things I have come to believe as "truth." One, shifting at 3000 rpm will save gas. I initially shifted at 4500 like you and got mid 15's on mileage. At first, 3000 shifts were psychologically hard for me but now I'm used to it. I occasionally run it up to 4500 or more if I gotta get around an idiot quick.

Second, using regular or premium will not affect your mileage. with regular, you will give up a few HP but you won't notice the difference. I and many others have tried, and can't tell. Plus I have an email from Mazda saying (1) It won't affect mileage and (2) It won't hurt the engine (by means of the anti-knock sensor.) I spent a lot of time running this to ground.

That ethyl methyl stuff can be found in any grade of octane, it's more a function of what brand of gas you buy. I'm still looking into this. Finally, the most imponderable of all is what did Mazda do -- if anything -- to the ECUs at the port? Did they tweak them or something for EPA thereby messing up both hp and mileage? At this point I think only Mulder and Sculley can unravel this mystery.

ULEV
 

the website of the dealer where i ordered my 8 has their inventory listed and 30 of the 93 rx-8's have ULEV in their description including mine. does this have any bearing on whether my car will be a gas hog or not?

I haven't read all the posts, but - I just finished a 6400 km road trip from Alberta to California and back - that's around 4000 miles. No babying, any cruising was done at 75 to 85 mph, and the slower stuff was including a lot of downshift/full throttle for passing on two lane roads or hard accelerating in the hills and twisties. Overall, I got 19.8 mpg, with the mileage at the end of the trip a bit better than at the start. The absolute lowest I could manage to get was 15.6 mpg, and several legs were at 22+ mpg.

Regards,
Gordon

What... you came all the way down here and didn't even drop in to say hi!? :D Hey, sounds like a great trip and thanks for the datapoints. Strange that you would be better mileage at the end. After all, it's downhill all the way from Canada to US and uphill all the way back, right?

My Mileage
 

Ok, I was pretty hard the on 8 for the first while aftder the break in.. I was pretty gentle with the 8 on break in, but that means nothing (more like very little) above 6000 rpm, and only a few 100% throttle stints.

my first fillup at 230 miles 13.5 gallons = 17.0 mpg

fillup #2, 200 miles, 13.3 gallons = 15mpg

I've always been getting the oil burnoff resudue on the inside of my muffler tips.. I'm wondering how heavily the inside of the exhaust (and cat?) are coated with that carbon deposit.

More recently (I've got 2500 miles on it now) I filed up at 223 miles for 12.5 gallons = 17.8 mpg.

The best mpg I've experienced so far, has been on a long drive from detroit to indianapolis. I achived 80 miles for each 1/4 tank marker. I filled up just after the light came on 13.8 gallons for 285 miles = 20.6 mpg (almost 100% driving at 80 mph)

I figure it should be possible to get 320 miles out of a full tank before being stranded on the side of the road.. ;)

I'm counting on Mazda to fix the crummy ECU setup. I'm going to call them and bitch about it. The dealer is just going to slow down my complaints. I've used only premium gas so far, and will definately try regular soon. I want my missing 50 horses (yes it could be that much) and 5 to 8 mpg back.

I figure the $500 madza is offering will only pay for the delta in gas costs from what they listed for about 6 months.. Planning to keep this car about 7 years means that they need to fork over another $6500 to make that up....

OverLOAD, the pattern you describe is starting to sound pretty typical. It's pretty much the same as me except I haven't taken an extended road trip yet. Good luck in your call to Mazda; let us know what, if anything, you get out of them.

MPG Bad
 

I thought that I would not care about MPG in the RX8 but
I have driven 1571.6 miles and put 108.6 gal, which is average of 14.5 MPG. Two tank full were freeway trips (18.7 & 19.1 MPG).
I admit that I run the air conditioner and stomp on it once in awhile (well maybe twice a day) and drive 70-90 MPH on the freeways but I have made an effort to go slow to see what the MPG should be and got pretty much the same 14MPG.
Yes I took care during the break-in. The break-in MPG was 12.7 to 14MPG.

I really like the RX8 but I may consider returning it and then buy one when things are more consistent. My Vin JM1FE173040106438.

From reading the forum, other are getting much better MPG. What is your experience?

One posting mentioned that MPG gets a little better after 2000 miles.

RX8 GT Blue

I may give the dealer a chance to see if they can find something wrong and also checkout my Air Conditioner (same problem as others). Although it is good some days and not so good others. I am going to place a digital thermometer in my car and take some data.

Re: MPG Bad
 

I'm going to merge your thread with the thread about this topic in the Tech Garage seciont. You'll get a lot more responses (and be able to read a lot more) in there.

All hwy mileage report - still poor
 

I've posted several time before in this thread re the mileage I'm (not) getting from my RX-8 - here is the latest update.

Yesterday I had to make a semi-local business trip for the day - 150 miles each way. The OD started a bit over 1000 miles. I filled up the night before and left the house in the morn - light traffic the entire trip. Filled again upon arrival - result: 20.4 MPG over 2.5 hours freeway cruising, 30% on cruise control, no air running.

For the reverse trip home: 19.4 MPG - ran the air the entire trip (needed in the afternoon), a bit more traffic than in the morn.

Both legs were run at the prevailing speed of traffic (which varied from 45 to 85 - I just went with the flow).

Gee, best my car can do is achieve City EPA estimates with 100% freeway driving under cruise control.

Alas, the theory re 2000 miles making a difference is something I probably won't have a chance to test - as I don't expect to get to 2k before the 10/1 decision deadline... The ineffciency of the car is making me lean toward selling it back. I don't want (or care about) steller MPG figures, I just want the car to operate as advertisedl... and I can honestly say that if the window sticker had said 13/19 (my averages) I never would have considered the 8.

Dave

Re: All hwy mileage report - still poor
 

Are you considering contacting Mazda customer support (phone)with your MPG issue? If so, I would be interested in hearing what they have to say. I was not planning on even starting work on my MPG problem until I hit my 3K checkup.

Anyway, good luck, and hope it turns out that you can get things resolved and keep the car!

Re: Re: All hwy mileage report - still poor
 

What they do is refer you to your dealer for a fuel consumption test. That consists of your dealer keep the car several days/up to a week and driving it around with instrumentation attached to verify mileage. Not sure what they do after that. Two of us (at least) have gotten this story.

We just got back from a trip from the DFW area to Chicago and back. Air was on all the time except for a few hours one morning. We averaged around 21 mpg. The best we got was a little over 22mpg when the air was off for about 1/2 tank. At least it's better than the 13 we've been getting in town.

I put in 1/2 quart of oil at 1300 and the other half at 2600 to keep the oil level light from coming on at high speed.

Re: All hwy mileage report - still poor
 

Ayup True dat!

What is considered high speed that your oil light is coming on?

Ya know it'd be interesting to see a Dyno of someone getting good gas mileage. Gotta wonder what their HP is and whether their dyno will have a Dip in it around 6700rpm.

Re: All hwy mileage report - still poor
 

You do know that that right there will take a big bite out of your highway mileage, right?

Remember, mileage at highway speeds drops off sharply above 60 MPH; the much-maligned 55 MPH speed limit wasn't chosen by throwing darts at the wall.

Run a tank on the highway at no more than the posted speed limit and see what you get...

The oil level light came on at about 78 and went out after slowing to about 74. The level on the dipstick was about 1/3 down from full.

I have about 1700 miles and just checked the oil again. It is right at half and I haven't added any yet nor has the oil light come on.
BTW I get it up to at least 80 everytime I take it out.

I think the later VIN cars have better baffling in the oil pan. My VIN is 2178 build 6/3 and I think I have the old oil pan which causes the oil light problem.

10xx VIN and 5/28 build. hmmm now what? :confused:

Anyway another fill-up today:
13.3 gallons and a whopping 214 combined miles traveled:

16.09 MPG and climbing :)

Re: Re: All hwy mileage report - still poor
 

Posted speeds are 70-75, maybe that's my problem. I need to see if Jeb will lower the speed limits again! :D

It's good that it's climbing. Weird that some cars start out with good MPG right out of the shoot while some have to "age". If all things were equal we could point to the ECU potentially assuming average driving patterns and obeying the break in period, etc. as being the culprit and holding the engine back until it was loosened up but that doesn't seem to be the case. Also at 2,000 miles things seem to really get interesting around 6000 rpm in terms of power. Keep us posted.

Isn't it possible that the older cars in the first allocation that sat at port for a few weeks were flashed with different ECU settings than later production cars? Maybe Mazda has come up with new, "better" settings after having a little more time to test/tweak.

I just wonder if that would help explain the differences we're seeing in mileage figures. My car was built 6/23/03 and so far I have been getting 22-23 mpg consistently after 19 the first tank. I've been driving pretty aggressively the last couple tanks and my highway speeds vary anywhere from 60-80. My daily commute is 80/20 highway/city, and I've got a little over 1100 miles on the car now.

Yes I agree this is a good explanation. I was looking at it as a static ECU for all cars but Mazda might be tweaking it as it gets more and more feedback.

Interesting good or interesting bad? I've had crappy gas mileage up till now, but at 2000 miles seeing my mileage start to improve. I have NOT had that power loss above 6250 that some have reported. Please don't tell me I'm gonna start seeing a power loss!

(btw, I have not been guilty of accusing people of inventing the 6250 power loss or not knowing how to drive. I wish those without the mileage or a/c problems would stop accusing those less fortunate of making this stuff up. It is really getting tiresome. This rant is not directed at RX-GR8, but many others in this forum.)

Interesting good. Sorry I should have been more explicit. I read on this forum some owners stating that at about 2000 miles the power seemed to increase at 6200 rpm whereas before the port seemed to be stuck or there was hesitation..

I think these people had a power problem at 6200 and ultimately the problem goes away. Since I'm not seeing that problem there should be no change for me. I think these theories about different versions of the ECU sound pretty plausible. This is the type of mystery I hope BOOSTD7 can unravel in his investigations with Mazda. If I have a substandard ECU burn, I'd like to know (1) Will my ECU sooner or later behave like those who are getting full power and full mileage, or (2) Can they reprogram my ECU to more favorable mpg's like some people seem to be getting from Day 1.

I am feeling your pain. I am keeping track on my latest fillup but its been awful so far. I've got about 500 miles on it and am beside myself on how bad the gas is. I would think the aluminum hood and pedals would push this thing to at least 40 mpg, don't you? Thats a joke.

Seriously, I demand at least 20. I will be gripping to the dealer too if I cant get it to at least 17. Below that is embarrassing, no matter how you drive. And I drive pretty conservatively.

I will look at the manual for the shift points though. But what fun is that. If I wanted some dang robotic shift points, I would have bought an automatic.

In desperation when I was getting 15 mpg I started following the recommended shift points, namely shifting at 3000 rpm. It was awful, just like you said. I did it for one full tank, got 16 mpg, did it for another half tank before I said the heck with it. It TOTALLY removes all fun from having the 8, for a gain of 1 mpg? I don't think so.

Now, I'm back to my old ways, but I've learned new bad habits (like efficient driving ;) ). I often shift now at 3K and I don't mind it so much anymore, but whenever I feel like it I rev it higher, meaning several times on any given outing. My mileage continues to rise (now up to 17.5.)

I am convinced that poor mileage has nothing to do with "bad" driving habits (within reason.) I've read many posts from people who regularly rev to 6K and are getting above 20 mpg without even trying. There are two versions of this car out there: Low mileage and high mileage. If I had to bet, it has to do with the ECU. I think we will get to the bottom of this, hopefully within the next few weeks (are you listening, Mazda?) because the polls on this forum show that more people are concerned about poor mileage than about less hp on paper. I would bet more cars will be returned for the mpg reason than for any other unless Mazda can help us sort this out.

yap
 

On the money 8_wannabe, as usual.

Gotsta be the ECU. Its the most plausible explanation, given the total confluence of info: the port hangup, the HP drop, and the drastic varation of MPG amongst different 8s. I wish knew how to check the firmware version. And, of course, I wish we knew how to flash it.

We creep closer and closer to October 1st, and Mazda continues to seemingly pretend this is not a problem. No recall. No TSB. Not even a quiet word to the dealers. They either don't understand the problem themselves, or they are living a fantasy that 8 owners don't really care about the MPG as much as this forum indicates they do, or they have already fixed the problem in new 8s, and are going to quietly let the buyback take care of the issue. I'm thinking its the later.

Since my car is one of the "sick" ones (and I don't mean "sick" in the newish positive form of the word . 13 MPG is the norm for my 8), I am leaning heavily in that direction. I will wait until the last week of September. If there is no fix at that time, my car is going back.

Great car. Lots of drama. This has to be one of the most fascinating new car experiences I've ever had. I am very happy to have the internet, and this forum. Think how screwed up all this would be if we couldn't communicate like this.

Re: Re: Re: All hwy mileage report - still poor
 

Well 75 is still lower than 85, so run a tank no faster than the posted limit and see if it makes a difference...

This is what I get
 

I drive on highway about 60 % of the time at 70 - 90 mph, and in the city at normal speed. I accelerate quickly a lot of the time, and run the A/C in 90 + weather all the time. I have about 700 miles on the car and I have been getting about 200-mpg average each tank of 91 gas. Just giving the facts for me.:)

So your getting what 12-14mpg, thats friggin terrible.

Well you are right
 

The mileage sucks but I did not buy it for the mileage. I love the drive and I do not give a damn about the mileage. I have a economy car for that. So your right the mileage sucks, but I love it anyway :D

That may not be true. It depends how low he's letting the tank go. I also have a little over 700 on my car and have been filling up about every 200 miles (when the meter is around 1/4 mark).

200 miles--11.696 gallons = 17.09 MPG
220.1 miles--12.551 gallons = 17.53 MPG
200 miles--13.055 gallons = 15.32


The big drop was due to hitting 600 miles on the car and bouncing off the rev limiter frequently :D


Edit: The first tanks were not granny style driving. Reasonably hard acceleration but less than WOT and shifting just under 6K RPMs.