EPA FE vs Actual FE

ForTheGlory · 02-26-2008, 06:45 AM

We all agree that the EPA fuel economy test is not representative of the type of driving that people actually do. The reasons for this are detailed elsewhere on this forum. Car manufacturers have an incentive to build cars that get good fuel economy, as the public is becoming more concerned with the gas mileage they're getting.

Do you think it's possible that a manufacturer might design a car such to get good fuel economy for the way that the EPA tests are performed (via specialized transmission gearing, engine design, etc), yet have good performance and poorer fuel economy under "normal" driving conditions?

I'm not sure that such a design is really possible, but the thought intrigued me. I plan to look at the difference in Fuel Economy between what the EPA estimates and what some third party (Consumer Reports) got in their independent testing for a number of vehicles with good fuel economy (>30 mpg). Big deltas between the two numbers obviously don't prove anything, but I think it would be interesting to look at.

I haven't done this yet, and probably won't do it until the weekend, but I wanted to post this before I forget.

**efusco** · 02-26-2008, 06:52 AM

Well, many would argue that the Prius was designed specifically to perform well on the old EPA test methods. Even if it wasn't designed with that in mind it did perform exceptionally well on the old EPA tests and hence a lot of people were disappointed when they found they got much worse than the promised 60mpg city.

The new EPA methods are pretty realistic and I think you'll have a nice bell shaped curve around the 48mpg EPA numbers for folks. Better yet the EPA provides a nice 'range' on the new window stickers specifically to cover the "YMMV" portion.

bwilson4web · 02-26-2008, 10:04 AM

Quote:

Originally Posted by ForTheGlory

. . . I plan to look at the difference in Fuel Economy between what the EPA estimates and what some third party (Consumer Reports) got in their independent testing for a number of vehicles with good fuel economy (>30 mpg). Big deltas between the two numbers obviously don't prove anything, but I think it would be interesting to look at.

I haven't done this yet, and probably won't do it until the weekend, but I wanted to post this before I forget.

You might look at the GreenHybrid.com mileage database. This includes a distribution of MPGs showing the various bell-like and non-bell curves of different vehicles.

GOOD LUCK!
Bob Wilson

NaptownPrius · 02-26-2008, 10:32 AM

I've commuted three days with my new Prius and my average is 54 mpg right out of the chute.

If it gets better, I'll be ecstatic.

I'm upset they changed the EPA numbers for '08. In my state (MD) an average less than 50 means I lose low emission vehicle exmption from yearly emissions testing.

Jack66 · 02-26-2008, 11:12 AM

Amazing! I just read Maryland House Bill 367 and am confounded as to why the lawmakers are following the letter of the law instead of the intent of the law. Prii made before 2008 are exempt because the window sticker has certain numbers on it. The 2008 is the same car emissions-wise but it has different numbers on the sticker so it isn't exempt. Maryland's legislators obviously do not understand the effect of the EPA changing its EPA reporting. It makes you wonder how they came up with 50 MPG as the magic number. Shouldn't they change the magic number with the new EPA standards? Or are they just partial to the number 50? Personally, 50 is one of my favorite numbers, but I wouldn't hang legislation on it...

bruceha_2000 · 02-28-2008, 11:27 AM

Quote:

Originally Posted by NaptownPrius

I'm upset they changed the EPA numbers for '08. In my state (MD) an average less than 50 means I lose low emission vehicle exemption from yearly emissions testing.

The PZEV rating doesn't count for anything?

Jack66 · 02-28-2008, 11:43 AM

Quote:

Originally Posted by bruceha_2000

The PZEV rating doesn't count for anything?

Apparently, the legislators are more concerned with upholding the number 50 than with what the number was supposed to represent.

02-26-2008, 06:45 AM	#1
ForTheGlory Senior Member Join Date: Feb 2008 Location: Maryland Posts: 296 My Car: 2008 Prius Model: Package: #6 Thanks: 0 Thanked 0 Times in 0 Posts Friends: 0	EPA FE vs Actual FE We all agree that the EPA fuel economy test is not representative of the type of driving that people actually do. The reasons for this are detailed elsewhere on this forum. Car manufacturers have an incentive to build cars that get good fuel economy, as the public is becoming more concerned with the gas mileage they're getting. Do you think it's possible that a manufacturer might design a car such to get good fuel economy for the way that the EPA tests are performed (via specialized transmission gearing, engine design, etc), yet have good performance and poorer fuel economy under "normal" driving conditions? I'm not sure that such a design is really possible, but the thought intrigued me. I plan to look at the difference in Fuel Economy between what the EPA estimates and what some third party (Consumer Reports) got in their independent testing for a number of vehicles with good fuel economy (>30 mpg). Big deltas between the two numbers obviously don't prove anything, but I think it would be interesting to look at. I haven't done this yet, and probably won't do it until the weekend, but I wanted to post this before I forget.

02-26-2008, 06:52 AM	#2
efusco Troll Slayer Join Date: Nov 2003 Location: Nixa, MO Posts: 18,055 My Car: 2004 Prius Model: Package: #9 Thanks: 102 Thanked 501 Times in 270 Posts Friends: 41	Re: EPA FE vs Actual FE Well, many would argue that the Prius was designed specifically to perform well on the old EPA test methods. Even if it wasn't designed with that in mind it did perform exceptionally well on the old EPA tests and hence a lot of people were disappointed when they found they got much worse than the promised 60mpg city. The new EPA methods are pretty realistic and I think you'll have a nice bell shaped curve around the 48mpg EPA numbers for folks. Better yet the EPA provides a nice 'range' on the new window stickers specifically to cover the "YMMV" portion. __________________ Evan E. Fusco, MD "It's a damn poor mind that can only think of one way to spell a word." -Andrew Jackson

02-26-2008, 10:32 AM	#4
NaptownPrius Getting Greener.... Join Date: Feb 2008 Location: Napolis, Merlin Posts: 214 My Car: 2008 Prius Model: Package: #4 Thanks: 0 Thanked 0 Times in 0 Posts Friends: 1	Re: EPA FE vs Actual FE I've commuted three days with my new Prius and my average is 54 mpg right out of the chute. If it gets better, I'll be ecstatic. I'm upset they changed the EPA numbers for '08. In my state (MD) an average less than 50 means I lose low emission vehicle exmption from yearly emissions testing.

02-26-2008, 11:12 AM	#5
Jack66 Kinda Jovial Member Join Date: Jan 2008 Location: Stafford, Virginia Posts: 766 My Car: 2008 Prius Model: Package: #2 Thanks: 0 Thanked 2 Times in 2 Posts Friends: 2	Re: EPA FE vs Actual FE Amazing! I just read Maryland House Bill 367 and am confounded as to why the lawmakers are following the letter of the law instead of the intent of the law. Prii made before 2008 are exempt because the window sticker has certain numbers on it. The 2008 is the same car emissions-wise but it has different numbers on the sticker so it isn't exempt. Maryland's legislators obviously do not understand the effect of the EPA changing its EPA reporting. It makes you wonder how they came up with 50 MPG as the magic number. Shouldn't they change the magic number with the new EPA standards? Or are they just partial to the number 50? Personally, 50 is one of my favorite numbers, but I wouldn't hang legislation on it...