EPA mileage figures going down
By James R. Healey
USA Today
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Fuel-economy ratings of cars and trucks will drop significantly starting with 2008 models, some of which go on sale early next year.
The declines are because the Environmental Protection Agency, responding to complaints by motorists and environmentalists, is using more realistic conditions to estimate mileage. The vehicles themselves, in most cases, haven't changed, only the fuel-economy testing.
Fuel-saving gasoline-electric hybrids drop the most — as much as 30 percent worse in city driving, 20 percent worse on the highway, EPA says. Averaged over all vehicles, city ratings will drop 12 percent, highway numbers 8 percent.
Big changes to the 31-year-old tests:
The new test includes hard acceleration. The old test used gentle acceleration.
That's another reason hybrids suffer. Hard acceleration requires full use of the gasoline engine and little or no participation by the fuel-saving electric motor. "It's not acting as a hybrid when you're accelerating like that," says Bill Wehrum of EPA's office of air and radiation, in charge of the testing.
Air conditioning puts a drag on the engine and increases fuel use.
The EPA and automakers refused to provide numbers for specific vehicles. But, for example, a 30 percent drop would cut the Toyota Prius hybrid's city rating to 42 miles per gallon from the current 60 mpg. A 20 percent drop would slice the highway number to 41 from 51.
If the Honda Civic hybrid fell the maximum, its city rating would drop to 34 mpg from the current 49 mpg, and highway mileage would drop to 41 mpg from 51.
Automakers will be allowed to include, through June, a line on the new window stickers saying what the ratings would have been under the old test.
The new EPA rules require fuel-economy numbers on medium-duty vehicles — those with gross vehicle weight ratings of 8,500 to 10,000 pounds — starting with 2011 models. Such vehicles aren't now required to post mileage numbers.
The new mileage tests don't affect what's known as CAFE, corporate average fuel economy, the average mileage of all vehicles sold by an automaker.
