JonsToy

Looks like we're not the only ones who aren't getting the mileage we expected

http://www.msnbc.msn.com/id/7128017/

How'd you like to own the Z4?

rx8wannahave

Yeah...someone posted this in another part of the website, the EPA has some explaining to do....

rx8wannahave

OK...EPA...re-do your test, it's outdated!

spork

They mention AAA has their own estimates. Does anyone know what the 8 is rated at? (by AAA)

Go48

Well, I checked on that and it's a bit murky since they don't express that information directly in miles per gallon numbers (go to the link below). Instead, they provide an estimated fuel cost of $6,018 for (I think) 75K miles over 5 years at a premium grade gasoline cost of $1.77/gal. Obviously old data.

If I understand their approach correctly, fuel mileage in MPG is arrived at by dividing the total fuel cost ($6,018) by the cost per gallon ($1.77) which equals 3,400 gallons. Then divide the total miles traveled (75,000 miles) by the total gallons used and that equals 22 MPG. Not significantly different from the EPA numbers. If the link below doesn't work, go to www.aaa.com and navigate through their pages to the page.

I'm not sure how AAA arrives at their estimates since as far as I know, they don't do any significant fuel mileage testing of their own. I suspect that their estimates are no better than EPA's.

http://ww2.aaa.com/scripts/WebObject....2.5.1.0.1.0.0

dmp

My car has been just about right-on w/ the EPA ratings of 18/23 (was it 23 on the sticker?).

I've been getting, while using 92 Octane fuel, 17/22 - I got 19mpg in town, (did no long-haul hwy test) on two tanks of 89 Octane.

LawFitz

Hey, I posted the following on another thread, but it seems appropriate here also. I'm trying not to complain, per se, about the MPG, just wondering if my low numbers are due to driving habits, low mileage on the car or what. Right now I love my 8. If I could get 20+ MPG in THIS CAR (please hold back any suggestions to get a different one), it would be all the more satisfying and I would feel less guilty about my guzzling ways.


Quote:
Originally Posted by bryrx804
well filled up again drove 323miles on 13.237gl..


Bryrx, that mileage is unbelievable. Literally. I have 1200 mi on my 8 - the best 1200 mi I've ever experienced BTW - and I'm averaging 15 MPG. I've been checking at every fill up b/c I'm a financial professional and **** by nature.

I'm still try to break the car in through 2000 mi (per advice from this forum), and thus am still shifting regularly at 4000 RPM, and rarely if ever go full throttle. Sometimes I may shift between 5-6K RPM, but usually it been between 3-4K.

I guess my question is how do you do it? Our central bank has been inflating the dollar since 2001 (see real estate, oil prices) and the effects will mean higher and higher gas prices for the foreseeable future. $3 premium will be here soon as the dollar continues to decline on world markets.

If I am able to get 20+ MPG somehow, I want to know how. If you're not BSing, you got 24+ on your last tank. HOW?

1. Did you always get such great mileage? What was it like when the car had <2K mi?
2. Do you shift at low RPMs and drive at minimal throttle only and never drive the car hard?
3. What is your freeway/city proportion like?

I want to make it clear b/c people will blast me that I luv the car and will deal with the 15 MPG if I have to. I just want to get better MPG if there's something I can do besides never driving the car hard. I mean, as it is, I'm being soft with her and only getting 15 MPG. What's gonna happen after 2K mi when I start shifting at 6-8K RPM with much more aggressive driving? Am I looking at 10-12 MPG???

klegg

I wonder why the EPA figures are so off? Does it have anything to do with the CAFE standerds?

And does anyone else think the EPA spokeswomen was a hot bit of tail....for a women her age?

RevTo9K

I read once that the EPA mileage is based upon some very non-world driving conditions - most notably, an average 0-60 time of over 16 seconds.

Here in the Chicago area drivers who do 0-60 in over 16 seconds are summarily executed.

dwynne

In order to make the tests consistant, all of the tests are done on a chassis dyno - not actually driven on roads. The "course" they "drive" has a city portion with stops of various lengths just like you would in town driving. The highway portion is at higher speeds with no stops. Then the actualy MPG is calculated for the test "drive" and then reduced to make it closer to real world. Lots of flaws with this test, the biggest is the "highway" test is done at 48mph and on a chasis dyno (no wind resistance). Even with correction, not too many of are going get highway numbers since we are going to be going a lot faster than 48 and fighing the air to do it. I think the city portion contains far too few stops compared to what most folks face in real world city driving. I can see where doing this in a controlled environment is needed, since if they test car A on a 30 degree rainy day and car B on a 100 degree day this is going to effect the results.

Since the testing procedure is published, the car makers do it for themselves and the EPA just double checks the numbers. I am not sure if they check (recheck) ever car or not. It is possible something with low production numbers (like a sports car) they may not bother to check.

There is already a move afoot to try to fix/correct this, the BlueWater Group (sounds like a bunch of tree hugging hippies, doesn't it?) has petitioned the EPA to fix this and the EPA seems to be listening.

http://www.epa.gov/fueleconomy/#regulations

One thing to note, if the car has a shift light then the person doing the test has to obey it. So the 'vette avoids the gas guzzler tax - it has a shift light that comes on if you don't wail the throttle in 1st gear, then when you pull back into "2nd" a solenoid diverts you into 4th gear. Since they are not really driving the car on a road, the result is nice EPA mileage. Also the 'vette has a super overdrive 6th (barely over 1,000 rpm at 60-65mph) so it shows good highway numbers. Just about none of the Prius owners gets anything close to the EPA numbers either. The Prius has an "economy" indicator and by rule the test persons tries to keep it lit. Most folks in the real world would not want to take 2 minutes to go from 0-60mph so they are not doing nearly as well.

As a reference to compare car A to car B I think it works OK - as long as neither has any tricky shift lights like the 'vette. If you are comparing the 2, generally the one with higher EPA numbers returns better real world economy as well.

I can drive my S2000 like I stole it and get 22-24 mpg AROUND TOWN and about 28 on trips - all with the top down. It does take premium, though.

Dennis