The new mileage calculation standards are especially important to Ford Motor Company because Ford will be among the first automakers to roll out its 2008 models, including the Ford Focus, Five Hundred, Escape and Escape Hybrid. The Focus and Five Hundred will debut next month at the North American International Auto Show in Detroit.

While the actual performance of '08 models will be similar to or better than the '07 models, starting in January, the estimates for city and highway miles-per-gallon (mpg) on all new 2008 model year vehicles will fall. Consumers will likely see estimates fall an average of two to four miles per gallon under the EPA's new calculations.

The new testing method, according to Stephen Johnson, an EPA administrator, will come much closer to "bridging the gap" between what the window sticker says and what consumers can expect in their fuel economy.

"This proposal gives consumers better information," said Johnson. "While there is no perfect test that can account for the wide range of climate and driving conditions consumers face, the new fuel economy ratings will be closer to what consumers actually achieve in real world driving conditions."

The Federal agency says its new testing methods will result in an average 12 percent drop in fuel-economy estimates for city driving and an average 8 percent decline in the highway rating. For hybrids, which are powered by a gasoline engine and an electric battery, the new city driving estimates could drop 20 to 30 percent. The decline in highway ratings could be up to 25 percent on some conventionally powered models.

The EPA has provided city and highway MPG estimates since the 1970s as a tool to help shoppers compare the fuel economy of different vehicles. The test methods for calculating these estimates were last revised in 1984, when they were also adjusted downward.

What has changed

"A lot of things," says Mike Fuher, Ford's certification supervisor in charge of fuel economy applications. "We have higher highway speed limits today than we did 20 years ago, and most vehicles now come with air conditioning as standard equipment. The new EPA methods now will better account for the impacts of these higher highway speeds and accessory usage."

In fact, Fuher says the changes being brought about by the EPA in all 2008 models are only the beginning.

"They also are implementing a 'phase two' that will go into effect with 2011 model year vehicles," Fuher said. "In addition to the standard city and highway dynamometer tests currently being used, some vehicles will undergo a broader range of testing under more extreme conditions, specifically, high-speed and fast-acceleration driving, along with the use of air conditioning (95 degrees Fahrenheit) and colder temperature operations (20 degrees Fahrenheit) with the heater and defroster on."

The EPA also is changing the design of the fuel economy label to make it more consumer-friendly. Manufacturers will be allowed a grace period to implement the use of its new fuel economy label design until September of 2007. But labels on all new 2008 models must immediately include new fuel economy ratings. For the earliest 2008 models, the old fuel economy ratings also will appear in small print, beneath the new city and highway estimates to allow for better comparison shopping against 2007 models.

"The most important element that consumers need to be aware of is when they do comparison shopping between one model year and another," said Usha Raghavachari, marketing manager for the 2008 Ford Escape, one of the first vehicles impacted by the change.

"Our dealers need to be sure that customers are aware of the changes and are making an actual 'apples-to-apples' performance comparison."

"It will only be a challenge if dealers and their personnel are not informed and equipped to handle it," said Kevin Collins, a second-generation owner of Bill Collins Ford in Louisville, Ky. "Frankly, I'm not sure how big of an issue this will be with customers, but we will get our team together and make sure they are aware of the changes that are coming."