Fuel Economy Ratings changed for 2008

[rh71]

http://www.fueleconomy.gov/feg/ratings2008.shtml

Initial thought: it's going to scare a lot of uninformed people.

 

[nakedfrog]

Interesting, the old numbers for my car are more accurate
The new estimates are lower, went from 22/30/25 to 20/27/22.

 

[rh71]

FWIW, I looked up my current '95 vehicle and the new 15mpg figure is much more accurate than the 'old' 17mpg figure. I've always gotten 14-15mpg on this thing.

 

[TimeKeeper]

good info! tks

 

[JulesMaximus]

The new estimates for my car are pretty close to reality. I get about 18mpg city and 24 freeway.

 

[ElFenix]

for my old taurus the EPA actually understated the highway mileage. it got 30 em pee gee. original ratings were at 29. new ratings have it at 26.

also seem less accurate for my sentra. the old ratings are 23/28/25, new rating is 20/25/22. average 24 in it, and 28 on the highway.

i still can't tell you why my taurus got better mileage than my 'economy car' sentra.

 

[Nyati13]

The new ratings seem less accurate, not more...

The old ratings had an 06 Subaru Forester "Mixed" at 25mpg, which is pretty dead on to what I get ( I average 25-26mpg every tank). The new rating is too low in my opinion/experience.

Same with my last vehicle. 99 Ford Escort, old MPG 32, I typically ran 34mpg, new MPG 28....

 

[nakedfrog]

And just so I understand it, this change has happened shortly after CAFE standards were increased?

 

[ElFenix]

Originally posted by: nakedfrog
And just so I understand it, this change has happened shortly after CAFE standards were increased?

this change has been in the planning for a while. dunno whether the 2007 stickers reflected the change, but the government's website has had both old and new ratings for a while.


the EPA uses unadjusted figures for CAFE purposes

even the old standard was adjusted.



http://en.wikipedia.org/wiki/Image:CAFEStandard.png

i wonder what that graph looks like adding in 2006 and 2007?

 

[overst33r]

The new ratings are more accurate for the majority of drivers. Apparently these days people maintain speed by using the brakes. :roll:

In my Corolla, I was getting 38mpg with 70hwy/30city driving. The old EPA estimate was 31/38. The new one is like 28/35 or something...

The Miata was originally rated at 23/29 but is now rated at 21/27. I manage 28mpg with the top down on said commute. I do a few redline shifts everytime I drive the car, so I'm not exactly driving like a granny...

People just have different driving styles. I'd say the EPA is doing a pretty good job estimating mpg, for most cars. There are always exceptions to the rule.

 

[Xyclone]

They go up to 80 mph and use the AC, I believe. They are much more realistic for the average driver.

 

[EvilYoda]

Yep, the changes are pretty extensive...this is something I have to explain quite often on the auto show floor.

 

[zerocool84]

Originally posted by: Xyclone
They go up to 80 mph and use the AC, I believe. They are much more realistic for the average driver.

Yep, who drives 55 on the frwy anyways???

 

[rh71]

Originally posted by: zerocool84

Originally posted by: Xyclone
They go up to 80 mph and use the AC, I believe. They are much more realistic for the average driver.

Yep, who drives 55 on the frwy anyways???

If you watch the vid, they say the methods used were from the 60s... when vehicles were much less powerful and the technology was different. It's not just the cruise speed alone.

 

[Vic]

The old ratings were more accurate for me. Can't say exactly why that is either, as my foot tends to be pretty heavy and I never use the cruise control.
I suppose it's because I don't drive with the AC on all the time all year...

 

[IronWing]

Originally posted by: nakedfrog
Interesting, the old numbers for my car are more accurate

Same here, at least for one car. The rating went from 19 to 18. My mileage is 19.3 mpg.

For the other car the change is accurate, sort of. My mileage did drop to 18, which is the new rating because I had a stuck choke which was allowing excess fuel into the engine. The old rating was 20 but I was getting 21 prior to the choke problem and I presume I'll get that again with the problem fixed.

 

[Zenmervolt]

Originally posted by: Vic
The old ratings were more accurate for me. Can't say exactly why that is either, as my foot tends to be pretty heavy and I never use the cruise control.
I suppose it's because I don't drive with the AC on all the time all year...

Shit, I drive with the A/C on and the old ratings were still accurate to slightly pessimistic. I've never had a car that didn't at least match the old EPA ratings. Most have done better than the old numbers.

ZV

 

[Throckmorton]

The highway rating for my Grand Cherokee is pessimistic. They say 13/17. I get more like 21 highway at 70mph, 25 at 60mph.

 

[SearchMaster]

For my '00 Maxima, old ratings=20/28/23, new=18/26/20. I have a pretty even 50/50 cty/hwy mix commute, and generally go 75-80 on the highway. I admit that I accelerate fairly slowly with fuel economy in mind but I almost always get 26-27mpg per tank.

 

[rh71]

Originally posted by: Throckmorton
The highway rating for my Grand Cherokee is pessimistic. They say 13/17. I get more like 21 highway at 70mph, 25 at 60mph.

That's nuts... I've never seen a mid-sized SUV get 25mpg, especially when it says 15 (as in your sticker avg). How did you calculate your numbers?

 

[JulesMaximus]

Originally posted by: rh71

Originally posted by: Throckmorton
The highway rating for my Grand Cherokee is pessimistic. They say 13/17. I get more like 21 highway at 70mph, 25 at 60mph.

That's nuts... I've never seen a mid-sized SUV get 25mpg, especially when it says 15 (as in your sticker avg). How did you calculate your numbers?

Me either. I had a '96 Isuzu Rodeo for a couple years and that thing never broke 17mpg on the freeway.

 

[JulesMaximus]

Originally posted by: SearchMaster
For my '00 Maxima, old ratings=20/28/23, new=18/26/20. I have a pretty even 50/50 cty/hwy mix commute, and generally go 75-80 on the highway. I admit that I accelerate fairly slowly with fuel economy in mind but I almost always get 26-27mpg per tank.

I hope you weren't going by what the computer said because mine is not accurate. According to my car it gets 21mpg average but in reality it's more like 18mpg. 2003 Nissan Maxima SE. The method I use to calculate fuel economy is fill up tank, reset trip odometer, drive until the tank is almost empty and fill up again. Divide number of miles driven by amount of gas put in tank to fill it back up. Reset and start over. I've done this hundreds of time since my car was brand new. I've never gotten much over 18mpg city driving in 67,000 miles of driving during the last 5 years I've owned the car. Most of my driving is stop and go city driving...I'd say 90% of it anyway.

 

[fbrdphreak]

I've tallied my computer & real world trip info from day one and the lifetime average is a 4.37% difference between the computer & actual MPG, with some tanks reading 10-15% off. The computer's estimate is just that...an estimate.

I'm sure some systems are better than others at estimating, but it just is not as accurate as consistent fill-ups from the same gas station and noting the amount of fuel to fill-up.

 

[Zenmervolt]

Originally posted by: fbrdphreak
I've tallied my computer & real world trip info from day one and the lifetime average is a 4.37% difference between the computer & actual MPG, with some tanks reading 10-15% off. The computer's estimate is just that...an estimate.

I'm sure some systems are better than others at estimating, but it just is not as accurate as consistent fill-ups from the same gas station and noting the amount of fuel to fill-up.

The computer should be pretty darn accurate unless you have replaced the injectors or are running a different fuel pressure regulator than stock. The mpg computers use injector duty cycle to determine the total amount of fuel delivered and the mileage recorded by the car's odometer.

Even the same gas station can have a large variation in how much fuel is delivered. Heck, even if you're using the same pump there can be a fairly big difference. The shutoff point is surprisingly inconsistent.

ZV

 

[JulesMaximus]

Originally posted by: Zenmervolt

Originally posted by: fbrdphreak
I've tallied my computer & real world trip info from day one and the lifetime average is a 4.37% difference between the computer & actual MPG, with some tanks reading 10-15% off. The computer's estimate is just that...an estimate.

I'm sure some systems are better than others at estimating, but it just is not as accurate as consistent fill-ups from the same gas station and noting the amount of fuel to fill-up.

The computer should be pretty darn accurate unless you have replaced the injectors or are running a different fuel pressure regulator than stock. The mpg computers use injector duty cycle to determine the total amount of fuel delivered and the mileage recorded by the car's odometer.

Even the same gas station can have a large variation in how much fuel is delivered. Heck, even if you're using the same pump there can be a fairly big difference. The shutoff point is surprisingly inconsistent.

ZV

Well, I can tell you exactly how much I've spent in dollars in fuel so regardless of what my computer tells me, my wallet tells me something completely different. I get at least 10% error between the computer calculated fuel economy and actual fuel economy in my car. That's a pretty fucking big difference.