AAA Study Shows Diesel Drivers Average 20 Percent Higher Than EPA Average
Gasoline Turbo Engines Lower Than Estimates, Manuals Higher
The accuracy of the Environmental Protection Agency (EPA) fuel economy estimates on new car stickers has long been debated, usually with the anecdotal conclusion that they’re wildly optimistic. A change in methodology and testing standards in 2008 adjusted the numbers lower, taking into account higher usage of air conditioning and higher freeway speeds. Most vehicles had their figures adjusted lower. Based on the self-reported figures, diesel drivers reported a fuel economy average 20 percent higher than the EPA estimate, according to an analysis of figures by AAA. The next-best category was vehicles equipped with a manual transmission, which achieved an average fuel economy 17 percent higher than EPA estimates.
Fitting with our own experience and others, gasoline-turbo I-4 and V-6 engines figures were four and nine percent lower than the EPA estimated average. For fans of the traditional V-8, fuel economy on V-8–powered trucks averaged five percent higher than the EPA estimates.
AAA reviewed more than 37,000 owner-submitted fuel economy figures to the EPA and paid particular attention to models with owner-reported economy 9 to 12 percent lower than the EPA estimated combined average. AAA engineers retested those models using certified emissions equipment to determine fuel economy using standard test methods.