AAA study: Owners top EPA ratings

Research by the American Automobile Association into the veracity of EPA ratings discovered that on average, owners who submitted information to the www.EPA.gov website claimed their vehicles exceeded rather than failed to meet the agency’s official mpg marks. While hastening to note that "self-reported data is of limited statistical use, as mileage calculation methodologies for these estimates cannot be verified," the AAA reported that owners in general claimed 12 percent higher real-world mpg averages than the EPA predictions. Of the over 37,000 who did provide data, 81.8 percent said their vehicles exceeded the EPA’s estimated combined figure, while 16 percent claimed worse averages and 2.2 percent found the numbers to be spot on. 

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Among other intriguing bits gleaned from this AAA study, owners of vehicles with manual transmissions claimed they exceeded the EPA index figure by 17 percent on average while those with automatics reported only a 7-percent upside bump. Minivan owners claimed EPA parity or slightly lower mileage numbers, but those driving diesel-powered vehicles enjoyed a whopping 20 percent economy bonus. Drivers of V6-powered sedans claimed a 9-percent advantage while owners of vehicles with 4-cylinder turbocharged engines averaged 4 percent less than posted EPA numbers. Trucks also produced anomalies. Owners of V8 models said mileage came in 5 percent ahead of what was expected on average while drivers of trucks fitted with V6 turbo engines reported falling 9 percent below the combined rating.