The new fuel economy standards are part of H.R. 6, the Energy Independence and Security Act of 2007, signed by President Bush on Wed. Dec. 19, 2007.
Bill H.R. 6 information: :./list/bss/d110HR.lst::|TOM:/bss/110search.html|
The fuel economy portion is also called the “Ten in Ten Fuel Economy Act.”
Basically, beginning with the 2011 model year, the Sec. of Transportation (with input from the Sec. of Energy and the Administrator of the EPA) shall start moving the CAFE standard up annually, until in model year 2020 it is at or over 35mpg. The law doesn’t state by how much it has to increase annually, just that it increases until 2020.

President Obama has just asked the US EPA and DOT to accelerate the existing 35mpg CAFE Bush mandate’s date of 2020 up to 2016.

Previous to the 2007 law, the last time that Congress set the fuel economy standards, was back in 1975 (when Ford was president), so moving the bar up from 27.5mpg for cars to 35mpg after 32 years shouldn’t be much of a problem. (Light trucks have always had a lower rating to keep.)

Remember that the MPG listed on the Monroney label (window sticker, also listed at) isn’t the fuel economy numbers used for the CAFE standards. CAFE uses the raw fuel economy numbers from the laboratory dynometer tests, but consumers only see the downward multiplied numbers to account for more “realistic driving.”

The CAFE standards are based on the city/highway average of the raw laboratory data, multiplied by the vehicle sales. The devaluation for the sticker/fuel economy label has no effect on the CAFE average. The more sales of a high-MPG vehicle, the more that’ll balance out sales of a low-MPG vehicle… So production numbers will probably change to include more of the fuel efficient vehicles to outweigh the sales of the less fuel efficient ones. Just like how manufacturers currently can sell vehicles that are less than the 25mpg fleet average so long as you have others to balance you out, the change to 35mpg doesn’t mean that all vehicles will have to be over 35mpg… Nothing about cars getting smaller or lighter or adding hybrid systems, but more about changing the mix of what is sold. Nothing about the existing cars prior to the 2011 model year.

Heavy trucks/work vehicles are not affected – vehicles with GVWR over 8,500 pounds aren’t tested for fuel economy.

You can view the raw EPA test data for various years, and an explanation of the columns, here:

For an example, let’s take the 2008 Toyota Highlander and the 2008 Dodge Viper Coupe.

lists for consumers:
TH 2WD: 18mpg city/24mpg highway
TH 4WD: 17mpg city/23mpg highway
TH Hybrid 4WD: 27mpg city/25mpg highway
DV Coupe: 13mpg city/22mpg highway

but using the 2008 raw data, which the CAFE standards are based on:
TH 2WD: 22.1mpg city/33.1mpg highway
TH 4WD: 21.2mpg city/31.3mpg highway
TH Hybrid 4WD: 35.3mpg city/35.2mpg highway
DV Coupe: 15.6mpg city/30mpg highway

So I wouldn’t expect much change in the cars being offered, but the availability of certain gas-guzzlers may be less.

The corvette may only get 20, but if GM makes more cars with 40+ MPG, they can meet the standard.