joeyr

Got this from MT It only part of the article as the rest was IMO was just rehash:

For the 2007 model year, cars sold in the U.S. averaged 31.3 mpg and light trucks averaged 23.1 mpg. Keep in mind that these numbers reflect a complex equation that takes a car or truck's "footprint" into account. Based on this equation, DOT says, Porsche will have to average 41.3 mpg by 2015 without buying another manufacturer's credits, or paying a gas guzzler tax (unless it can by then count the fuel economy of every Volkswagen AG model sold in the U.S.), whereas newly independent Jaguar/Land Rover will have a lower number to achieve for cars, because Jaguars make a larger "footprint."

This is to prevent an automaker from simply switching to small cars. Even Honda and Volkswagen, traditionally the automakers with the highest fleet averages, will have to show technology improvements to get better fuel mileage from Fits and Golfs. Because of their mix of vehicles, Ford Motor Company will have to reach higher numbers than Toyota/Lexus/Scion. Those numbers (which still assume Jaguar/LR as part of FoMoCo):

FORD
MY 2011: 31.0 mpg
MY 2012: 32.7 mpg
MY 2013: 33.7 mpg
MY 2014: 34.5 mpg
MY 2015: 35.5 mpg

TOYOTA
MY 2011: 30.1 mpg
MY 2012: 31.5 mpg
MY 2013: 32.7 mpg
MY 2014: 33.6 mpg
MY 2015: 34.6 mpg

Those are eye-opening numbers, because it means, on the face of it, that the average Toyota has a bigger "footprint" than the average Ford.