EPA MPG Estimates are Seriously Flawed - Page 2 - Fuelly Forums

Android Users - Coming Soon! - Migrating from aCar 4.8 to 5.0

Reply
 
Thread Tools Display Modes
 
Old 05-09-2011, 02:46 PM   #11
Member
 
Join Date: Oct 2011
Posts: 43
Country: United States
Re: EPA MPG Estimates are Seriously Flawed

The 1983, 1984 and 1985 Diplomat are essentially the same so I just used the 1985 numbers.

The thing is none of those fuel mileages use hypermiling techniques. Just moderate acceleration, run the speed limit and dont "charge" redlights or stop signs.

I almost always do better (compared to estimates) on larger more powerful vehicles and struggle to make the estimates on smaller less powerful vehicles.
__________________

GeneK is offline   Reply With Quote
Old 05-09-2011, 03:29 PM   #12
Registered Member
 
imzjustplayin's Avatar
 
Join Date: Dec 2011
Posts: 720
Country: United States
Re: EPA MPG Estimates are Seriously Flawed

Quote:
Originally Posted by Tightwad View Post
The 1983, 1984 and 1985 Diplomat are essentially the same so I just used the 1985 numbers.

The thing is none of those fuel mileages use hypermiling techniques. Just moderate acceleration, run the speed limit and dont "charge" redlights or stop signs.

I almost always do better (compared to estimates) on larger more powerful vehicles and struggle to make the estimates on smaller less powerful vehicles.
Sounds like to me you do a lot of highway driving.. Large vehicles with big engines are very capable of getting good numbers, so good it sometimes makes you question the value of those "smaller cars". However the strength of smaller cars tends to be in city driving since they tend to weigh less and therefore have less inertia. I mean I can get 38mpg in a Volvo S60 I drive which is rated at 22mpg combined, though I have to be cruising at 55mph. In a Honda Civic, cruising at the same speed and route, best I think I can get is 50mpg and that is rated at 30mpg combined. I've heard of at least one guy with a Buick Lesabre also getting 38mpg but I think they were driving faster than 55mph..
__________________

imzjustplayin is offline   Reply With Quote
Old 05-10-2011, 08:32 AM   #13
Registered Member
 
Join Date: Nov 2007
Posts: 1,461
Country: United States
Location: north east PA
Re: EPA MPG Estimates are Seriously Flawed

Quote:
The thing is none of those fuel mileages use hypermiling techniques. Just moderate acceleration, run the speed limit and dont "charge" redlights or stop signs.
For the average driver, those are hypermiling techniques.
trollbait is offline   Reply With Quote
Old 05-11-2011, 03:54 PM   #14
Member
 
Join Date: Oct 2011
Posts: 43
Country: United States
Re: EPA MPG Estimates are Seriously Flawed

Quote:
Originally Posted by trollbait View Post
For the average driver, those are hypermiling techniques.
Hypermiling to me means. Pulse and Glide, Costing with engine off, Rolling out of throttle on up hills to barely crest hill, using gravity to accelerate, windows up with no ac in 80F+ Weather, drafting, never using a drive through, engine off at redlights. 40 mph max speed to optimize fuel mileage in high drag vehicle, etc.

I think my 15 mile and 25 minute commute should best be described as suburban. The lights are every 1/4 to 1 mile instead of every 100 yards.

I dont know what Im doing wrong with the Accent. I just dont seem to get any better with it than the Mustang on the same commute.
GeneK is offline   Reply With Quote
Old 05-16-2011, 04:59 AM   #15
Junior Member
 
Join Date: Jul 2012
Posts: 10
Country: Australia
Location: Blue Mountains NSW
Re: EPA MPG Estimates are Seriously Flawed

I've just come across a 1980 EPA fuel economy certificate (on the internet) for a Datsun 280zx, 3 speed auto, 2 seater.
It's the closest thing to my model I've found so far, the main difference being mine is the 4 seater and therefore a bit heavier.
The fuel rating is 19 mpg.
My fuel economy (before hypermiling) ranged from 20.8 to 19.6 mpg (spirited driving) and my last tank returned 22 mpg.

So yes, these ratings are only a guide. Even driving like a rat bag I was slightly above their figure.
The disclaimer reads "Your own mileage may be poorer depending upon options, driving conditions, your driving habits and your car's operating condition."
22over7 is offline   Reply With Quote
Old 05-16-2011, 07:22 PM   #16
Registered Member
 
imzjustplayin's Avatar
 
Join Date: Dec 2011
Posts: 720
Country: United States
Re: EPA MPG Estimates are Seriously Flawed

Quote:
Originally Posted by D.O.G. View Post
I've just come across a 1980 EPA fuel economy certificate (on the internet) for a Datsun 280zx, 3 speed auto, 2 seater.
It's the closest thing to my model I've found so far, the main difference being mine is the 4 seater and therefore a bit heavier.
The fuel rating is 19 mpg.
My fuel economy (before hypermiling) ranged from 20.8 to 19.6 mpg (spirited driving) and my last tank returned 22 mpg.

So yes, these ratings are only a guide. Even driving like a rat bag I was slightly above their figure.
The disclaimer reads "Your own mileage may be poorer depending upon options, driving conditions, your driving habits and your car's operating condition."
Your 280ZX is rated at 21city 26hwy, 23mpg combined; CAFE.. Which means its 1985-2007 or 2008+ fuel economy rating is significantly lower than that.. If you're able to average 23mpg doing 45% highway 55% city driving without ANY hypermiling techniques, then you're doing very well..

http://fueleconomy.gov/feg/download.shtml
001 3806015042 3 21 26 23 1107 168A3-1 6 FIAY 20.5489 26.1966 22.7566 6 280ZX 2+2 (FFS)

An approximate conversion... 22.5mpg CAFE=17mpg 2008 estimates, 20.5mpg CAFE=15mpg 2008 estimates, and 26mpg CAFE=19mpg 2008 estimates. So I guess using the 2008 estimates, your car is rated at 15mpg city, 19mpg hwy and 17mpg combined.
imzjustplayin is offline   Reply With Quote
Old 05-17-2011, 04:18 AM   #17
Junior Member
 
Join Date: Jul 2012
Posts: 10
Country: Australia
Location: Blue Mountains NSW
Thumbs up Re: EPA MPG Estimates are Seriously Flawed

Quote:
Originally Posted by ************* View Post
Your 280ZX is rated at 21city 26hwy, 23mpg combined; CAFE.. Which means its 1985-2007 or 2008+ fuel economy rating is significantly lower than that.. If you're able to average 23mpg doing 45% highway 55% city driving without ANY hypermiling techniques, then you're doing very well..

http://fueleconomy.gov/feg/download.shtml
001 3806015042 3 21 26 23 1107 168A3-1 6 FIAY 20.5489 26.1966 22.7566 6 280ZX 2+2 (FFS)

An approximate conversion... 22.5mpg CAFE=17mpg 2008 estimates, 20.5mpg CAFE=15mpg 2008 estimates, and 26mpg CAFE=19mpg 2008 estimates. So I guess using the 2008 estimates, your car is rated at 15mpg city, 19mpg hwy and 17mpg combined.
WOW!! Thankyou so much for that. I've been looking for fuel economy figures for this car for ages.
I didn't explain myself too well in my previous post. The pre-hypermiling figures were from two years ago, when I first bought the car. The 22 mpg is from this month, I haven't kept records inbetween.
Is there a particular formula for converting the "old" ratings to the "new"? I'm curious to see the different ratings for the life of this model.
Thanks again,
Pete.
22over7 is offline   Reply With Quote
Old 05-17-2011, 04:45 AM   #18
Registered Member
 
theholycow's Avatar
 
Join Date: Apr 2008
Posts: 6,624
Country: United States
Send a message via ICQ to theholycow Send a message via AIM to theholycow Send a message via MSN to theholycow Send a message via Yahoo to theholycow
Re: EPA MPG Estimates are Seriously Flawed

Boy am I glad to see that link and that interpretation of data! I couldn't find that link anymore, and I really wanted a way to get some kind of estimates for my car.

It looks like you're using 75% of the rating from 81FG.DAT.

From 80FG.DAT for the only LeSabre 4.1 listing I found:
100 4440 8030 6 17 23 20 794 252A3-1 6 4AY 17.3891 23.2655 19.6190( 4.1L) 7 LESABRE

Looks like my 2008 EPA rating would be around 13 city, 14.5 combined, 17.5 highway. BRB putting that in my garage data...
__________________
This sig may return, some day.
theholycow is offline   Reply With Quote
Old 05-18-2011, 04:45 AM   #19
Registered Member
 
Join Date: May 2011
Posts: 4
Country: United States
Re: EPA MPG Estimates are Seriously Flawed

I may be wrong about this, but I heard that vehicle manufactures base their MPG on a vehicle doing 55mph on flat ground. Which may be why under different conditions you get lower MPG.
Zalittle is offline   Reply With Quote
Old 05-18-2011, 06:06 AM   #20
Registered Member
 
theholycow's Avatar
 
Join Date: Apr 2008
Posts: 6,624
Country: United States
Send a message via ICQ to theholycow Send a message via AIM to theholycow Send a message via MSN to theholycow Send a message via Yahoo to theholycow
Re: EPA MPG Estimates are Seriously Flawed

Manufacturers base their MPG on the very specifically documented tests that the US EPA requires (and the EPA spot-checks to keep them honest).
http://fueleconomy.gov/feg/how_tested.shtml
http://fueleconomy.gov/feg/fe_test_schedules.shtml
__________________

__________________
This sig may return, some day.
theholycow is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
fuel-up entry suggestion fugalaya Fuelly Web Support and Community News 3 04-12-2009 09:29 AM
2006 Jeep Grand Cherokee rh77 Car Reviews 0 01-24-2007 08:38 AM
YAY! The fit is here! Matt Timion General Discussion (Off-Topic) 45 10-21-2006 02:43 PM
LaPointes new products.... ZugyNA General Fuel Topics 6 09-02-2006 05:22 AM
Greetings from Japan. GasSavers_Diemaster General Discussion (Off-Topic) 8 07-13-2006 07:56 PM

Powered by vBadvanced CMPS v3.2.3


All times are GMT -8. The time now is 06:06 AM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.