Overall, the respondents said their real-world fuel economy averages 12 percent higher than the combined city/highway EPA ratings for their vehicles.
Those who drive diesel-powered vehicles reported fuel economy that was 20 percent better than the sticker; owners of manual-transmission models said they got 17 percent higher mileage; drivers of V6-engined sedans reported 9 percent better fuel economy; and owners of V8-powered trucks found that they improved on the sticker rating by 5 percent.
Minivan owners said their fuel economy was equal to or slightly lower than the EPA ratings, while those who drive vehicles with turbocharged four-cylinder engines reported mileage that was 4 percent lower than the ratings and those with turbocharged V6 engines said their fuel economy was 9 percent lower.
The report debuted at a time when fewer American consumers appear to be concerned about vehicle fuel economy. Car shoppers are opening up their wallets to buy bigger, better vehicles and often more thirsty vehicles, according to a new Edmunds marketing analysis.
Many are heading out for the annual summer road trip and enjoying relatively low gas prices. AAA said in early June that consumers should see the cheapest summer gas prices since 2009.
The AAA Daily Fuel Gauge Report on Wednesday pegged the average price for a gallon of unleaded gasoline at $2.80 versus $3.66 a year ago.
The U.S. Energy Information Administration expects gas to average $2.43 a gallon during the second half of 2015.
But for car shoppers who still put fuel economy up high on their list of concerns, the AAA study provided a major boost.
For the study, AAA said its engineers conducted a comprehensive analysis of 37,000 records submitted to the EPA on its FuelEconomy.gov Web site, representing more than 8,400 vehicle make, model and year combinations, to identify trends in real-world fuel economy.
"The vast majority of drivers that submit their vehicle's fuel economy to the EPA report mileage that beats the window sticker rating," said John Nielsen, AAA's managing director for Automotive Engineering and Repair, in a statement. "Although self-reported data has limitations, it's encouraging to see real-world fuel economy that more closely aligns with, or even exceeds, automaker promises."
During its analysis, AAA identified three vehicles that were frequently reported to return fuel economy lower than the EPA sticker rating. Although AAA didn't identify these models by name, they were a 2014 full-size pickup, a 2014 large sedan and a 2012 midsize sedan.
Submitting these vehicles to dynamometer and on-road testing revealed that the fuel economy of all three "slightly exceeded" the EPA ratings.
From these tests AAA concluded that "an individual's driving behaviors, including speed, rate of acceleration and braking, along with vehicle condition, driving environment and terrain are likely responsible for deviations from EPA ratings," rather than any shortcomings attributable to the vehicles themselves.
"If you drive aggressively, with heavy acceleration, hard braking and driving at higher speeds, your fuel economy is going to suffer," said Nielsen. "Driving just 5 mph above 50 is like paying an additional 19 cents per gallon for gasoline."
AAA plans to continue its testing to measure the impact that specific driving behaviors, such as acceleration rates and idle time, have on an individual driver's fuel economy. Results of the next phase of the study should be released by the end of this year.
Edmunds says: This AAA study sheds some interesting light on the impact our driving behavior can have on fuel economy.