Consumer Reports did an amazing, comprehensive study of all of their test cars' actual achievable mileage. Check out the results. It's no surprise that real-world mileage is well under EPA mileage. However, the differences, particularly for city mileage, are striking. The hybrids, for example, still beat everything else, but they're not nearly as far off from other small cars.

Yeesh. Countdown to a class action suit anyone?

I'm sure that all of those ratings are achievable. It's just that almost all drivers are much more leadfooted than that.

Who do you sue? The government mandates a very specific testing methodology. The automakers follow the rules and, I believe, aren't allowed to present alternative data. Consumer Reports, however, has no such restriction.

My prelude is rated at 27 on the freeway and I get 26 overall with mostly freeway, some city and very little attention to gas miliage. I've got no complaints there.

The hybrid system is apperently extreemly well suited at getting high EPA numbers while delivering much worse actual miliage. Great if you're selling cars with the miliage plastered in the window, not great if you're planning on getting those figures. Try as I might, I've never been able to get 60mpg in my friends prius, and if I'm getting close to that I'm draining the batteries and it's going to start turning on the engine extra to charge them up.

Can anyone find the exact description of the EPA test? I've never seen any sort of description of what's required, and my google-fu is lacking.

Matthew

Do you think these results are at least relative to the advertised mileage? That would be all that would matter to me. If I bought a new car, I wouldn't compare it's EPA rating to real-world results on my old car. Instead, I'd pretty much just observe the difference in what I was paying on average for gas

Did they test other cars, like minivans? The new Odyssey suprised me recently. I could be totally wrong here, but I could swear that I read somewhere that it was possible to select to only use four of the engine's six cylinders in order to save on gas. I don't know if this is true or how it is done, but it's an interesting idea...

There are several engines out there that do that these days. I know Tony's V8 Hemi in his Charger is supposed to do it, but I think it's automatic. They call it the Multi-Displacement System.

Interesting idea, not new.

EPA testing:

How Vehicles are tested
Driving routine graphs

They also have a list of popular cars which aren't required to be tested by the EPA (because they weigh too much). It includes the Hummer H1 and H2, the Ford Excursion, the Chevy Suburban and Avalanche, and the GMC Yukon, plus some pickup trucks and vans.

Okay, here's how it's defined in the US Code of Federal Regulations.

40CFR600