Sign in to follow this  
Followers 0
Ledopmi

New EPA Fuel Mileage Estimates less accurate

13 posts in this topic

I just don't see how the new estimates are supposed to be more accurate. Every vehicle I have owned has shown mileage equal or better than the claimed mileage, and I drive hard compared to 99% of the people on the road.

My 2001 Trans Am six speed was rated at 19/28, now it is rated at 17/25. I have kept an Excel spreadsheet since I bought the car new in 2001 which I tracked the fuel economy since day 1. This cars will see 31mpg strictly highway driving with an average speed of 80mph.

I drive 24 miles round trip to work and home with 12 stops, and speeds ranging from 30 mph - 60 mph. When I accelerate from a stop, I usually will be about 10 car lengths ahead of the other cars around me by the time I reach speed. Most people take forever to get to speed. Driving like this, I usually average 19-20mpg. I tried a few experiments where I accelerated as slow as everyone else and I averaged 24mpg.This is without the skip shift 1st to 4th feature. I use every gear.

I only saw 17 mpg one time and that was when I made a lot of runs at the race track.

My 1985 Corvette Auto was rated at 16/23 and is now rated at 15/21. This car can see 24mpg with only highway driving and back and forth to work I see 18mpg with the way I drive. I have not experimented driving slow like most other people.

(I now have a new engine with AFR heads, a large cam and a 3200rpm torque converter so my mileage has dropped to 22 on the highway and 17 back and forth to work.)

My 1987 Suburban 4x4 was rated at 13/16 and is now rated at 11/15. This truck has seen 16mpg on the highway. I do not drive it to work but overall it averages 12-13 mpg.

I had a 1989 Celebrity 2.8 that was rated at 23/30 and is now 21/28. I say 30mpg highway and 24mpg to work and home.

I had a 1991 Honda Civic CRX 1.6 that was rated at 28/33 and is now 24/30. When I drove this car to work, I accelerated at full throttle almost every time. (That is what it took for acceptable acceleration in this car) I still averaged 30mpg. I never got any highway estimates on this car but it would surely be a LOT better than 30mpg.

I had more cars but did not keep accurate mileage for them except for my 83 3/4 pickup, but there are no official numbers to compare it to.

0

Share this post


Link to post
Share on other sites

I recently got ~16.5 on a tank of full city driving...a few miles a few ways, work, school, home. mostly home, work. the cold hurts my car pretty bad sometimes... but i also think my accelerating upto 2k or barely over doesn't help. gonna try to get up to 2.5K at least and see where that gets me next tank. but i need to change my oil too. :( that'll ruin my experiment. my oil now is ~6 months old and may have 2.5k miles on it.

0

Share this post


Link to post
Share on other sites

It really depends on whether you do rural or urban driving. I keep reading about how people get 30+ MPG in their 528i, Passat, or Odyssey, when in fact I only get 18, 21, and 16 MPG, respectively.

All cars do surprisingly well at constant speeds. It's red lights, traffic, and acceleration that kill the fuel economy of any non-hybrid. I used to average 24 MPG on runs to a particular Barnes & Noble; lately, with all the holiday congestion, I could only average 17.5 MPG. I literally watched my average MPG drop from 32.4 MPG (high after a mile of coasting downhill) to 28.0 MPG during one traffic light!

0

Share this post


Link to post
Share on other sites

eh my Goat gets 18 if i run the hell out of it, 21 city and 29-34 highway(ranging from 60-85 mph) so if someone would like to tell me what the new one for the Goat is ill probably just end up laughing.

0

Share this post


Link to post
Share on other sites

2005 400hp GTO Six Speed Was 17/25 Now 15/23

2005 400hp GTO Auto Was 16/21 Now 14/19

2004 350hp GTO Six Speed Was 17/29 Now 16/26

2004 350hp GTO Auto Was 16/21 Now 15/20

0

Share this post


Link to post
Share on other sites

The only ACCURATE way to gage gas mileage is to set the odometer to zero, run the gas tank to as empty as you dare, then fill it up yourself, see how many gallons you used, then do the math. If you average that out after 3 or so tanks, you should have a fairly accurate reading. Summer a/c and winter cold driving really wreck the averages, though. I do a combination of city and highway and average only 30 (Imperial) mpg on my Optra, which is horrible, but I am hard on my vehicles, especially a 2.0 litre engine! Interestingly, that is the same average I used to get on my '87 Shadow with a 2.2 turbo 4 and 5 spd manual, so maybe the Opra with the slushbox is not so bad.

0

Share this post


Link to post
Share on other sites
2005 400hp GTO Six Speed Was 17/25 Now 15/23

2005 400hp GTO Auto Was 16/21 Now 14/19

2004 350hp GTO Six Speed Was 17/29 Now 16/26

2004 350hp GTO Auto Was 16/21 Now 15/20

From your descriptions (and that's all I have to go on), you're not comparing apples to apples. The EPA's test is not steady-state highway use, which would get BETTER gas mileage than their "highway" estimate. Your commute sounds more like how the EPA describes their "highway" estimate. And their "city" estimate is, I assume, full of MORE starts and stops than your commute.

I, too, have always done better than EPA with most of my cars (my Merkur being the exception).

0

Share this post


Link to post
Share on other sites

How are you coming up with these 'was' and 'now' figures for out of production cars??? The new EPA mileage estimates only apply to new cars, don't they?

0

Share this post


Link to post
Share on other sites
I just don't see how the new estimates are supposed to be more accurate. Every vehicle I have owned has shown mileage equal or better than the claimed mileage, and I drive hard compared to 99% of the people on the road.

My 2001 Trans Am six speed was rated at 19/28, now it is rated at 17/25. I have kept an Excel spreadsheet since I bought the car new in 2001 which I tracked the fuel economy since day 1. This cars will see 31mpg strictly highway driving with an average speed of 80mph.

I drive 24 miles round trip to work and home with 12 stops, and speeds ranging from 30 mph - 60 mph. When I accelerate from a stop, I usually will be about 10 car lengths ahead of the other cars around me by the time I reach speed. Most people take forever to get to speed. Driving like this, I usually average 19-20mpg. I tried a few experiments where I accelerated as slow as everyone else and I averaged 24mpg.This is without the skip shift 1st to 4th feature. I use every gear.

I only saw 17 mpg one time and that was when I made a lot of runs at the race track.

My 1985 Corvette Auto was rated at 16/23 and is now rated at 15/21. This car can see 24mpg with only highway driving and back and forth to work I see 18mpg with the way I drive. I have not experimented driving slow like most other people.

(I now have a new engine with AFR heads, a large cam and a 3200rpm torque converter so my mileage has dropped to 22 on the highway and 17 back and forth to work.)

My 1987 Suburban 4x4 was rated at 13/16 and is now rated at 11/15. This truck has seen 16mpg on the highway. I do not drive it to work but overall it averages 12-13 mpg.

I had a 1989 Celebrity 2.8 that was rated at 23/30 and is now 21/28. I say 30mpg highway and 24mpg to work and home.

I had a 1991 Honda Civic CRX 1.6 that was rated at 28/33 and is now 24/30. When I drove this car to work, I accelerated at full throttle almost every time. (That is what it took for acceptable acceleration in this car) I still averaged 30mpg. I never got any highway estimates on this car but it would surely be a LOT better than 30mpg.

I had more cars but did not keep accurate mileage for them except for my 83 3/4 pickup, but there are no official numbers to compare it to.

It is quite common for one person to get well above or well below averages. You might be in a low altitude area with low humidity and cool temperatures. That alone would increase mileage noticeably. Whether or not that is the case; the point is there are many factors that affect mileage, and the EPA estimates have to be indicative of a nationwide average.

0

Share this post


Link to post
Share on other sites
I am wondering the same thing moltar is... where in the heck is the OP coming up with these "new" figures on old cars? I didn't know there was a strict formula for the "new" numbers v. the "old" when the EPA does their calculating. The "loss" in mpg varies by vehicle, as far as I can tell, there is no strict "percentage".
0

Share this post


Link to post
Share on other sites

I'm just curious... what would my 94 Century be rated? I happen to know its actual rating (I did a few tests with it recently), despite its issues.

0

Share this post


Link to post
Share on other sites

The new estimates for older cars are real "estimates" of the new estimate (which is actual performance under the new test, which itself estimates driving behaviour in certain conditions), they haven't actually been tested under the new system (which still makes certain assumptions which vary from vehicle to vehicle and may not be equally reliable).

0

Share this post


Link to post
Share on other sites

Your content will need to be approved by a moderator

Guest
You are commenting as a guest. If you have an account, please sign in.
Reply to this topic...

×   You have pasted content with formatting.   Remove formatting

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

Sign in to follow this  
Followers 0