One fully expected those gathered Wednesday in the White House rose garden -- environmentalists, captains of the global auto industry and government officials -- to break out into a rousing chorus of Kumbaya.

Everybody, including dueling parties normally at odds, expressed their delight with President Obama's announcement of the more stringent and earlier-than-planned fuel-economy and emissions standards that would be applied from sea to shining sea.


However, as in all things involving politics, the new fuel-economy standards aren't what they seem.

"Turns out that there are loopholes almost big enough to drive an SUV through," quipped Edmunds.com CEO Jeremy Anwyl.

It starts with the math -- two different mathematical formulas used by two agencies of the U.S. government.

One mathematical calculation is used for mileage ratings under Corporate Average Fuel Economy (CAFE) rules. Quite another is used by the Environmental Protection Agency (EPA) to figure the fuel economy ratings on window stickers for new cars.

"CAFE miles per gallon ratings and EPA window sticker mpg ratings were originally generated simultaneously through government lab testing," said Edmunds.com Director of Vehicle Testing Dan Edmunds. "Window sticker ratings have been down-rated twice in the last 25 years to make them more realistic for consumers, while CAFE mpg methods remained the same. So, with each EPA revision, EPA window sticker mpg and CAFE mpg drifted further apart."

Indeed, the difference between the two is significant -- big enough to drive an SUV through in some cases.

For example, a vehicle that scores an EPA rating combined city/highway of 29 miles per gallon actually contributes 39 mpg to its manufacturer's CAFE average.

The new 35.5 mpg by 2016 standard announced by President Obama translates to about 26 miles per gallon. While that lower number may be disappointing environmentalists, it explains why automakers, including the Detroit-based ones, so gleefully signed on -- it's far less Draconian than one might think on first blush.

In fact, according to Edmunds.com's analysis, 29 car models and 36 truck models already achieve the new standard, and about a third of the cars and half of the trucks are produced by a domestic automaker. A full list of those models is available at Edmunds.com's GreenCarAdvisor.com.

Edmunds' GreenCarAdvisor.com Editor John O'Dell originally reported on this discrepancy in December 2007, in an article entitled "Fuel Economy: Doublespeak at its Best." In that piece, O'Dell wrote, "Most people have been trained to think only of the EPA numbers when talk turns to fuel economy, and they aren't aware of the differences between the EPA and CAFE figures. That makes the standard a little misleading."