Here'* a little something I read on EPA ratings in an article in Motortrend, about a roadtest comparison with the gas-electric hybrids. The information about how the EPA does the testing is the same for regular cars. Here'* some quotes from the article:
"...those numbers are generated in the comfort of a test cell, and real people--even fuel-economy nuts driving with the proverbial egg on the accelerator--have been largely unable to match them out in the cold, cruel world. Informal Internet poling among hybrid user groups suggests actual mileage averages of around 40 for the Civic, the mid-40s for the Prius, and 50ish for the Insight. Our own one-year hybrid fuel-economy averages have been even lower. Why is this?
The EPA test procedure is grossly out of date. It was designed around the cars, test equipment, and traffic flow of the carburetor age (late 1960s) and chiseled in granite by 1975. The 11-mile city test includes 23 stops, with a maximum speed of 56 mph, an average speed of 20 mph, and about five minutes of idling. The 10-mile highway test averages 48 mph, peaks at 60 mph, and includes no intermediate stops and minimal idling. Correction factors were introduced once, in 1985, reducing the city figure by 10 percent and the highway figure by 22 percent in an attempt to reflect real-world driving."
So as you can see, the EPA rated numbers on the window stickers are considerably higher than what you'll experience in the real world. Sucks, I know. I've been wondering how some of these guys are pulling out 31mpg trips out of their SSEi'* and I can't get over 23 on average.