The air down here

THE NATIONAL HIGHWAY TRAFFIC SAFETY Administration recently proposed a modest increase in mileage standards for cars, pickup trucks and SUVs, providing commuters a little -- but not much -- hope for relief as they pump $3-per-gallon gasoline into their tanks.

Buried in the proposal, though, is a blast of foul air aimed directly at California, which had the temerity to adopt rules that might produce more efficient cars and light trucks. “We reaffirm our view that a state may not impose a legal requirement relating to fuel economy, whether by statute, regulation or otherwise, that conflicts with this rule,” the proposal declares. “A state law that seeks to reduce motor vehicle carbon dioxide emissions is both expressly and impliedly preempted.”

At issue is a 3-year-old California law that requires manufacturers to slash emissions of greenhouse gases from cars and light trucks sold in the state, starting in 2009. Under the federal law governing mileage standards, the states cannot regulate fuel economy. Period. California’s law is a back-door attempt to increase mileage standards, opponents say, because the only way to reduce carbon dioxide emissions from cars and trucks is to burn less gasoline per mile. But the federal Clean Air Act gives the state the unique ability to adopt tougher anti-smog rules than the Environmental Protection Agency issued for the rest of the nation. State officials insist that its greenhouse-emission rules are directly tied to California’s severe air-quality problems. The federal courts will eventually decide who’s right.

Judging by the traffic safety administration’s stance, Washington is ready to weigh in against Sacramento’s clean-air effort. It’s becoming something of a habit for the Bush administration, which previously supported challenges to California’s zero-emission requirements and the South Coast Air Quality Management District’s mandate that operators of truck and bus fleets buy cleaner diesel vehicles.

The administration is trying to have it both ways. In mid-2003, it denied a petition to regulate greenhouse-gas emissions from cars, then successfully defended that decision against court challenges filed by California and 11 other states. And now that California is taking matters into its own hands, the administration is telling it to pipe down.

At stake is more than just California’s regulations. Seven northeastern states and Washington and Oregon are poised to follow California’s lead. That kind of shift could force widespread changes in the way cars and light trucks are built -- and cause a much more meaningful reduction in emissions than a single state could compel.