LawFitz

Okay a lot of numbers are flying around regarding the cost of fuel consumption by our thristy 8's. Here's my take.

- I'm averaging 15 MPG (actually, 14.XXX)
- Below is the cost per 10K miles for various MPGs - I will likely put 15K per year on the car, so I need to multiply the number below by 1.5 to get an annual fuel cost. You will need to assign your own multiple to come up with an annual cost based on YOUR expected miles driven per year
- I'm assuming various gas prices, but we can expect $3 per gallon as reasonable. Remember in Europe, they're paying $5+ per gallon right now and here in the States, we've been devaluing the dollar for 3+ years to keep our economy "humming." As a result we've seen huge rises in home values, other asset values, commodity values (including, yes, oil), and a long decline in the value of the dollar against other currencies. Futures contracts are now saying that high oil and gas prices are here to stay.

20 MPG; $3 gas -
>10 mi cost: $1500

15 MPG; $3 gas -
>10K mi cost: $2000
>cost over 20 MPG: $500

12 MPG; $3 gas -
>10K mi cost: $2500
>cost over 20 MPG: $1000

***

20 MPG; $4 gas -
>10 mi cost: $2000

15 MPG; $4 gas -
>10K mi cost: $2667
>cost over 20 MPG: $667

12 MPG; $4 gas -
>10K mi cost: $3333
>cost over 20 MPG: $1333

These numbers tell me that if I only get 12 MPG (which I expect since I'm babying my car during break-in, but can't break 15 MPG currently) after I start driving her harder, I can expect to pay an extra $10K for the car over the first 100K miles than those of you who are averaging 20 MPG!!!

This is why I'm pissed off to hear that my particular RX8 is averaging so much less than you. I luv the car, don't get me wrong. But if I know I am paying an extra $5-10K for mine (assuming 12-15 MPG and no discounting to present value) than those of your with 20 MPG, then I'm salty.

Maybe I need to talk to Mazda about my particular ride. All I know is that my last car was getting 23 MPG easy and the new reality of 12-15 MPG hurts.

Sorry for the extended rant, but I think those of you who are getting 20 MPG seem to think that the rest of us are being trivial for complaining about 15 MPG. An extra $500 per 10K miles tells me that we are not. If prices rise above $3, then we're even more f'd.

my final $.02... hopefully.

I luv the car but don't even get me started on what the differences are between 12-15 MPG and 25+ MPG. Those numbers can get real ugly very quickly.

As a final note, I will argue that this is why the 8 has has not been selling well, both new and used. Just look at Ford and GM during the past two months. Both have had sales tank b/c people have stopped buying SUVs this year... I wonder why?

rodmeister

I don't mean to be argumentative, but the RX-8 is a SPORTS CAR. Selecting a car involves weighing all the compromises and tradeoffs that are important to you. You can't have everything in one car. A Porsche costs too much; the 300Z didn't have enough interior space and was too crude; the I300 was too ugly; the G35 felt tinny; the Mercedes 325 is too common, etc. If gas mileage, and $500 dollars a year is that important, get a Prius.

alnielsen

iTrader: (4)

Let me put it this way. If some people are getting over 20 mpg and others are getting 10 mpg, then there must be a problem with the cars getting the lesser gas milage. I don't wan't to hear the suck it up, its a sports car argument any more. The milage issue is a symptom of a problem that needs to be taken care of. It is a question of effecincy.

capnfrantic

Lawfitz makes agood point. In reference to "If gas mileage, and $500 dollars a year is that important, get a Prius." some of us could add $100. to that and have our insurance paid for a year. Not trying to start anything but my Z is averaging 19 MPG.
The "it's a sports car" theory does'nt fly. The biggest thing I have noticed with the 8 is the margin of difference in reported MPG. JMO

LawFitz

Rod, the Prius is a horrible comparison. That car gets what, 40 MPG?

The difference between 40 MPG and 15 at $3 gas is $1250 per 10K mi and $1750 for 12 MPG. Per 10K mi, not per year! I drive about 15K per year.

Don't compare this to the Prius. Compare it to other "sports" cars in this price range. Compare my 15 MPG to all those who get 20 MPG on their RX8's like I did above.

What do the WRX, RSX Type S, 350Z, A4 quattro, and S2000 get? If any of them get 25 MPG, then the difference per 10K miles using $3 gas is $1300. For 100K miles (what i had intended for this car) the difference is $13,000. If any of these cars gets more than 25 MPG or if my car ends up with less than 15 MPG, then it's even worse.

I can send you my spreadsheet. I've set it up to easily calculate the TRUE cost differences.

I'm tired of the SPORTS CAR argument. The mileage on this car sux period.

I'm not going to sell b/c the 2ndary market will kill me, but if I knew this I probably wouldn't have bot the car. Here's hoping she will at least stay at 15 MPG and not get any worse!

Howard

This is the issue in a nutshell. As far as I know I have not read anywhere where service is resolving the problem or any sensible answerl. My dealorship is wonderful and will do anything to resolve any issues I have. The have been unable to find a solution and Mazda has made no effort to work with them. Mazda simply is not giving them any answers to what they think the problem is. On the other hand they are not denying there is a problem. The service manager and the Tech both see a problem and not with just my car but they have no ansers and are waiting for MAzda to come up with one. If MAzda is aware there is a problem with some of these vehicles they either need to recall those vehicles or compensate the owners. According to the figures previously mentioned 10,000.00 would be about right. The reality is Mazda will do nothing because to replace one vehicle or compensate one owner will require them to resolve the issue for everyone with the problem. If they did that they might just loose all the profit they have made on the RX8 and it would have horrendous efects on all of Mazdas future sales. To place the blame on the EPA is ludicrous. Even though they set the figures it is Mazdas responsibility to resolve a difference when it is this large. If the Food and Drug Administration approves a drug does it remove any responsibility from the manufactor if a problem is later found to exist. Of course not. MAzda has a responsibility to its buyers to inform them of the actual mileage.

Mugatu

iTrader: (1)

oh boy!

another gas mileage thread.

dwynne

To get a good handle on the variances you really need a trip computer - like my BMW has.

I can track "consumption" (MPG) in 2 resettable counters, but also "average speed". The consumption the computer measures is really close to what I calculate for my MPG by taking the trip meter and dividing by the gallons at fill up (to the first full click). I find that the average speed goes hand in hand with variances in consumption and my calculated MPG. For example, with school in session we leave the house at a certain time and rush hour is pretty heavy (only a 15 minute window to drop one son off at school). On those weeks/days my average SPEED is 24-25mph for the tank and my average MPG is 14 or so. If I take highway trips (like running to the dealer on the other side of town to look at an 8 during lunch) then my average SPEED for that tank will go up a few MPH but my MPG will go up as well. On school closed days, I take a different route and maybe drive at a different time and my MPH goes up as does my MPG.

So the first thing in trying to compare mileage with someone else is to know what their average SPEED was for the tank. Just saying "I get 12 mpg around town" or "I get 20 mph around town" is not a good comparison if the 12mpg driver takes 45 minutes to drive 10 miles to work and the 20mpg driver takes 30 minutes to drive 20 miles to work.

On the S2000, I get 21-22mph commuting in mine with school in session (I get 14-15mpg in the BMW) - and I figure the average speed in the S would be the same as the BMW- around 24-25mph for the tank. If I am not stuck idling in traffic I can get 24mpg or better "in town" and 26-28mpg "out on the road". Just cruising on the interstate for a trip would net pretty close to 30mpg.

If you go check the Prius owner's web pages you will see that a LOT of them are not getting even close to claimed EPA MPG on their cars either. You have to really poke along in them to get that much and most of the drivers are not used to the "style" and so don't get nearly what they thought they were going to get. The EPA test rules say if there is an economy indicator they drive to keep it lit, if there is a shift indicator they shift when it says to shift. So cars with these "tricks" (like the Prius) can make a LOT better on EPA tests than most folks will ever get - unless they drive by the light/indicator which equals poking along.

Dennis

ptiemann

Yes, those numbers are scary. E.g. I drove 27k miles last year. Gas is not $3 but $2.50 but ..
let's look what it does over the lifespan of the car and let's just assume 100k miles.

12 MPG; $3 gas -
>10K mi cost: $2500
>cost over 20 MPG: $1000

100k mi cost: 25000
cost over 20 mpg: 10000

Now some may say that the rotary engine needs less maintenance (e.g. no timing belt or chain to be replaced) and thus saves money there. But not $10,000!

Personally, my RX-8 gets now 19 mpg on average, so I'm not too upset - not happy either.

I don't think Mazda will do anything. Nor do they HAVE TO.

My suggestion: Sell it and get another RX-8. You'll be losing $2000 or so but it's worth it.

Or do what I did. Get a second car (beater). Filled mine this morning, 7.4G after 340 miles (46 mpg). The $450 that I paid for this vehicle were paid off after 6 months of using it.

-Peter

m82492

I think we should all do what Mazda is doing about the problem and what our government is doing about the ridiculous price of gas.......IGNORE IT AND MOVE ON

dwynne

There you go, just park the 8 and it gets an infinite MPG :D

Seriously, I don't mind driving my '96 Subaru Legacy L on snow days or rainy days, but I REALLY do not want to drive it every day. I guess I COULD get a "My other car is an S2000" plate frame or something......

Dennis

rodmeister

When I bought my RX-7 I knew the mileage would be bad, but on balance, the RX was what I wanted. Same with the RX-8. Having relatively low mileage is the price I paid for the RX-8 and the rotary. Buyers should take it or leave it. The gas price difference wouldn't convince me to buy the 300Z, I300, or other car.

But the previous posts do have a point that there shouldn't be a DISPARITY between RX's, from 10mpg to 20mpg. Mazda needs to take the 10mpg car and have a 20mpg driver drive it to determine if driving styles cause the difference, though I personally doubt the driver could double mpg.

In the mean time I'll just enjoy my RX-8 and not worry about mileage. Ask me later if gas goes to $5.00/gal.

(BTW, I get 15mpg. I once got 18mpg with 100% highway driving.)

LawFitz

Rod, I would divorce my wife and marry the car right now if I could get 20 MPG.

At 1500 miles and grandma (break-in) driving, I'm just under 15 MPG. I didn't buy this car to drive it like a grandma, but the thought of 12 MPG or worse, when others are claiming 18-20 while driving hard is what's getting to me.

I guess I'm screwed.

Some have mentioned the MPG getting better with age, but I can't see my car going from 15 MPG to 20 MPG over time. That just seems way unrealistic.

I'll keep you posted.

Slick8

While most of you are worrying about nickel and diming gas mileage and oil consumption, stop your nagging beotches!!! Take a look at the actual cost to own an RX-8 compared to other competitive vehicles:

Vehicle Average Cost per Mile
RX-8 $0.49
350Z $0.56
330Ci $0.63
G35 $0.57
WRX STi $0.59
EVO MR $0.63
RSX Type-S $0.44
Mustang GT $0.56
Grand Am $0.49
IS300 $0.53
S2000 $0.52

Referenced from Edmunds.com based on 2005 models, a five-year period and 15,000 miles per year...

LawFitz

Slick,

Edmuds is basing that figure on a higher resale value and a higher MPG than is appropriate for the 8. If they used 13-15 MPG with much worse resale than expected (as will be the case if gas prices continue to climb over the next few years), I bet their cost per mile would be much higher.

Doing the math sux, but I just don't trust sites like Edmunds anymore. Those sites are the ones that convinced me that I could reasonably expect 20 MPG.

I should've read this site more thoroughly.

I guess I'll just have to suck it up and enjor the car. It's costing more like a $40K car than a $30K car but what can I do now? Dam* spilled milk.

spork

I was told it takes up to 6000 miles for the car to settle and get you the real mileage but I'm at almost 5000 and it's the same as always. (~16.5 mixed).

But yeah I know what you mean. If I AVERAGE 19 or 20mpg mixed driving, I'm jumping for joy. I'm leasing my 8 and I'd definitely buy it if I average 19/20. As is, I'm iffy.

I'm pretty sure if most people averaged 19 or 20 mixed, I really doubt we'd see 80% of the mileage threads. The disparity is just crazy. I really want to know what the reason is for it though. Driver? Mechanical problem? Amount of trips per day? Outside conditions?

But anyways, you should have fun with your car. You'll be surprised how the occassional "spirited" drive doesn't do that much damage to your mileage (but I'm sure frequent spirited driving does). You're past Mazda's recommended break in, have fun with it a bit.

Slick8

Lawfitz, the average fuel economy was 17.5 mpg for the RX-8 long-termer on the Edmunds site. If the cost of gas goes up, so does the average cost of all the other the cars proportionally.

Spork, you think your losing money in gas mileage??? The real issue and bigger impact to your bottom line is that your leasing the RX-8... the cost of leasing far surpasses and overshadows the difference in lower gas mileage.

Q-chan

iTrader: (1)

You have to understand how the rotary engine works. It is very different from a piston engine. It needs a different driving style:

The rotary is most efficient under partial load at a mid-range RPM. If you drive it "Gandma Style", with relatively high load at low RPM,
that is bad for the engine, and worse for the gas milage.

You have to shift gears *VERY* frequent to keep it in the optimal power range. Doing so, I enjoy 18-21 mpg in mixed town and highway driving.
The torque characteristic of the Renesis engine allows you drive very "Grandma-style", but you pay for your lazyness at the pump.

Also, it is very wrong to drive a car (no matter what engine) "Grandma" during break-in. You should avoid excessive high revs, but you should
even more avoid a "Grandma" style of high load at low RPM. The best break-in is to take your new toy on a 500 miles fun trip on a highway,
driving moderate speed with variable mid-range RPM.

Slick8

I drive my RX-8 quickly and take advantage of the handling characteristics, but NEVER abuse it. My gas mileage is ~18mpg, give or take 3mpg for city versus highway driving.

NomisR

What's the mileage you get when you don't drive like a grandma though?

When I drive, I usually just rev the **** out of it, at least shifting at 6k or so and still get 18-20 mixed driving. However, you have to remember that mileage will increase greatly over time, if you're just at 1500miles, may be the case. Also, for this engine, i don't think you're suppose to grandma it during break in. From the owners manual, it never mentioned to keep it under XXXX RPM like they do with piston engines, only thing is to vary the RPMS which I hope you did.

Anyways, try driving it like you should, you'll like the car a lot more. However, note that I did have a tank of 13-4 mpg, that was simply all city driving although I did take it on a couple runs though the canyons, it's still "city" I suppose.

Vertigo-1

iTrader: (3)

So what's the ideal RPM to be cruising at then? 3000 vs. the typical 2000 that pistons cruise at? Anything over 3700, and you are plainly opening up the secondary fuel injectors, so I don't see how driving higher than that will help the MPG.

swiftnet

I get anywhere from 12mpg to 18mpg. In my case,the answer is pretty simple. .
If I drive over 110mph and/or keep the rpms above 7000 I get low mpg. If I keep the car below 60mph and/or keep the rpms under 4500 I get 18mpg.
I travel a fast highway where 80-90 is pretty normal, when I have a safe opening (no cars in front) I often hit 120mph. My gas mileage is pretty poor most the time, but when I take an alternate route where travel is at 45mph, I get decent gas mileage. Like I said, the answer is pretty simple, in my case.

dwynne

Looks like bogus numbers to me. They used a sports pack 8 (lower cost so lower depreciation) and they use the EPA fuel numbers, which we know are wrong.

BTW, folks must not have read the reviews if they didn't know up front about the bad mileage. Consumer Reports got 14mpg city, 22 highway, 18 overall, 20 mpg for their 150 mile loop. The z got 16/30/22/24. The S got 27 mpg overall. Even Edmunds notes how poor the mileage is - thought the EPA does not look that bad.

Of course, Edmunds lists the Volvo C70 as a "top rated" car to hold value. Volvo could not sell the 04s so they dropped them. One of the local dealers has 14 of them on the lot right now and still can't sell them for $7k off!

Dennis

dwynne

Not really, it depends on the money factor of the lease - AND you are assuming you will get a good ROI on your car if you try to sell it. With a lease you pay for the part of the car you use - your lowest negotiated price VS the lease bank's prediction of future value. We pretty much know now that the future value will be poor. With lots of still unsold 04s on the lots, $4,000 in rebates, $2,000 in dicounts on 05s (if you lease) it does not look good. In fact, today a dealer offered me my choice of any 04 they have left for $5,000 under DEALER COST. So a sports pack car would be $21,500, touring for $22,800, GT for $23,900, GT w/NAV for $25,600. With the lease the future value is guessed - if the car holds value BETTER than expected you can buy it off the end of the lease for a "discount". If the car does not, then just turn it in - or negotiate a lower buyout price. With a cash purchase, it is not as big a deal (other than just losing money quicker). But with a long term loan - 60-72 months weak resale due to all these cheap NEW cars means you will be upside down a LONG time if you try to come out of the car.

Dennis

spork

Oh I know leasing isn't great. But the lease + residual value + tax is slightly higher than what it would've cost if I bought it outright. I really wanted to buy but I leased on advice from my mom who pointed out that it was the first model year for the car. Then I thought a bit about it and realized... well it's a brand new model with a brand new engine and the RX-7 was known to have plenty of issues. What happens if it's just a maintenence nightmare? I won't know the long term reliability of the car by the end of my lease but at least I can see the general trend at first. So to play it safe I leased.

I'm not that worried about the money lost at this point actually. First and foremost I want to know what causes the bad mileage. Is it a bad part? Which part if so? Is it me? What do I need to change in my driving to pump up the mileage? (And as I stated in other threads even when I do all the typical gas saving techniques that have been suggested time and time again I don't get close to 18city). But obviously if I got 18/24 I'd be much happier... and the money I'd save would definitely be appreciated. It's not much, but hey if someone gave you an extra few hundred a year I'm sure it'd make you happy.