EPA Fesses Up About Gas Mileage. So Should DOT.

Congress has to change the law before Department of Transportation can change how it calculates its fuel standards for carmakers.

Published: 16-Jan-2006

ong last, the Environmental Protection Agency has decided to tell the public the truth about fuel mileage. The agency proposes to change the methods it uses to rate vehicle fuel economy to reflect real-world driving conditions better. Unfortunately, the sensible new rules proposed at the EPA will not affect the way the Department of Transportation calculates fuel standards for manufacturers who produce the nation's cars.

For years, experts have scoffed at the government's fuel ratings for how they are based more on laboratory conditions and not those in the real driving world. Consumers Union, which publishes Consumer Reports magazine and is a leading critic of the government's fuel testing regime, conducts its own tests. In the fall, the magazine reported that the EPA's fuel efficiency ratings were off for 90 percent of about 300 cars and trucks the CU tested for the 2000 to 2006 model years. In some cases, the CU's tests showed that the government understated fuel consumption by as much as 50 percent.

EPA administrator Stephen Johnson conceded as much when he announced the agency's proposal to change the methods it uses to determine miles-per-gallon estimates. For the first time, the EPA will consider what really happens behind the wheel, specifically, how car air conditioning, high speeds and cold temperatures impact fuel consumption. In addition, the EPA will adjust its testing to account better for things such as road grade, wind, tire pressure and the effects of different fuel properties.

Under the new methods, the EPA expects gas mileage estimates for most cars will drop by as much as 10 percent to 20percent under city driving conditions and 5 percent to 15 percent on the highway. Fuel ratings for those popular hybrid cars are expected to decline even further, perhaps 20 percent to 30percent. For some time, fuel economy experts have known that batteries used in hybrids are more sensitive to the energydepleting effects of air conditioning and cold temperatures than conventional cars.

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