Such a move would have the setting of fuel economy standards move from traditional transportation officials to the environmental regulators, and has only come about because of a recent U.S. Supreme Court ruling. The EPA has been in charge of regulating auto emissions for years, but this would be the first time its policies would have an effect on the levels of fuel consumption.
Under the stipulations of Bush's original 20-in-10 plan, manufacturers would have to improve the mileage of cars by 4% a year between 2010 and 2017 and the same 4% a year for trucks between 2012 and 2017. As expected, automakers consider such a proposal as being too harsh, citing the fact that cars would have to average 32 mpg in just 10 years ,when today's average is just 24mpg.
[Source: Automotive News - Subs. Req'd]