Very few consumers actually achieve the fuel economy posted on their sticker. The EPA itself has admitted that real-world fuel economy is usually about 20 percent lower than its own lab numbers.
Part of this is due to the quirky provisions of the testing procedures, and part is because a whole new generation of clean diesels, hybrids and electrics has rendered the testing protocol outdated, if not obsolete.
Bottom line: the EPA should either scrap the rule altogether or — at a minimum — repair it so it’s more in keeping with the fuel economy achieved by real people driving on real roads.
To save costs, automakers are able to submit a single fuel economy number for all their vehicles with the same weight, engine and transmission, even if the outer sheet metal of the vehicles may be different.
The lab tests are done by placing vehicles on a mechanical treadmill called a dynamometer. Thus, the testing doesn’t take into consideration factors like individual driving styles, temperature or geography.
The test cycling of the dynamometers is also a bone of contention. Since the EPA test cycling favors city driving, many owners of hybrids say their real-world fuel economy is far less than the EPA numbers.
There have been class-action lawsuits over the discrepancies and even a “restating” of hybrid fuel economy by a major automaker.
Ironically, diesel owners point out that their vehicles — which generally are more efficient in highway driving — frequently do better than the EPA posted number.
Another factor that distorts the EPA numbers from real-world fuel economy is the fuel the agency uses in testing. It contains no ethanol.
Gasoline that we purchase today at gas stations across the country contains as much as 10 percent ethanol – which the EPA says can lower fuel economy by about four percent. It would seem logical that the EPA should use gasoline in its testing with the same ethanol content as that purchased by motorists when they fill up their tanks.
A cynic would say all the factors listed above indicate the vast bureaucracy of the EPA has gotten itself all tangled up in its mandated task of providing accurate fuel economy estimates. And the fact that so many consumers are not getting the advertised fuel economy is a sign that something’s clearly out of whack.
It’s no wonder the auto industry is quick to point out: “Your mileage may vary.” But consumers need valid mileage numbers to make valid buying decisions. Under the current standards all they have is confusion.
Most consumers would contend that vehicle fuel economy is a key factor in their purchase decision. When shopping for a car or truck, it’s a good thing to be aware of the vehicle’s efficiency — particularly at a time when gasoline prices tend to be so volatile.
That’s why the EPA has a responsibility to get the numbers right.
Noack is a retired General Motors executive who writes about automotive issues and trends.