How the EPA Determines A Vehicle’s Gas Mileage
August 4th, 2006 | by Brian Carr |I came across an interesting article on the U.S. Department of Energy’s Fuel Economy website about how the Environmental Protection Agency goes about calculating a car’s fuel economy - you know, the numbers car manufacturers always brag about on their commercials.
When the EPA tests a vehicle’s gas mileage, they do so in a very controlled environment, placing the vehicle on a treadmill like device. From there, they are able to simulate driving conditions and use the collected data to make their gas mileage estimates.
When I read this article, the testing process sort of came as a shock to me. Maybe I’m naive, but I just assumed that when the EPA would test a car’s fuel economy that they might actually take it out for a drive!
Don’t get me wrong, I understand that in order to compare apples to apples, these tests need to be performed in a very controlled, sterile environment. However, this certainly doesn’t seem to mirror actual driving conditions.
Although, there’s a reason why I’m writing a blog and not actually out doing the testing - I’m sure the people who put together this laboratory are far more intelligent than I and have thoroughly thought everything through.
3 Responses to “How the EPA Determines A Vehicle’s Gas Mileage”
By sakanagai on Aug 7, 2006 | Reply
There was a study conducted by some European publication that checked the mileage of popular “fuel-efficient” automobiles. In general, fuel economy is a tad less (in the case of the Prius, a LOT less; about 15 mpg), but mostly less than 2 mpg difference. Also, the DOE website, I believe, is trying to better inform consumers that many new cars have a “break-in” period where they should not expect peak fuel economy.
By Brian Carr on Aug 7, 2006 | Reply
Thanks for the comment.
I guess that’s what I was trying to allude to in my article - the fact that lab conditions are never going to mirror actual on-the-road conditions.
Although, that may be the less important part. I think the lab can probably do a half way decent job of mirroring driving conditions, it’s the bad driving habits that are hard to simulate!
By sakanagai on Aug 7, 2006 | Reply
Good point. I know that while I’ve tried to better my habits over the past few months, I have the occasional slip. Also the bad driving habits of others can’t be controlled. A slow driver in front of you can prevent you from driving in a higher gear.