"The White House would not divulge details, but environmental advocates and industry officials briefed on the program said that the president would grant California's longstanding request to implement its tailpipe standards. Thirteen other states and the District of Columbia have said they intend to apply the same rules. That request had been denied by the Bush administration but has been under review by top Obama administration officials since January.
Yet Mr. Obama is planning to go further, effectively issuing a single mileage rule for both fuel economy and emissions that matches California's strictest-in-the-nation standard.
Under that new standard, the national fleet mileage rule for cars would be roughly 42 miles a gallon in 2016. Light trucks would have to meet a fleet average of slightly more than 26.2 miles a gallon by 2016.
"This is a very big deal," said Daniel Becker of the Safe Climate Campaign, a group that has pushed for tougher mileage and emissions standards with the goal of curbing the heat-trapping gases that have been linked to global warming. 'This is the single biggest step the American government has ever taken to cut greenhouse-gas emissions.'"