Responding to a new front in the ongoing battle over fuel economy, major automakers are stepping up efforts to defeat a California law that would pre-empt federal gasoline mileage standards, according to a Detroit News story by Jeff Plungis. The proposal, which has been passed in California's Assembly and is pending in the State Senate, would give the California Air Resources Board (CARB) broad authority to regulate automobile carbon dioxide emissions as a pollutant. The industry's latest challenge comes several weeks after a significant victory in Washington, where attempts in Congress to adopt stricter fuel economy rules were defeated. Under the current, so-called Corporate Average Fuel Economy (CAFE) law, automakers' U.S. car fleets must average 27.5 miles per gallon, while light truck fleets must average 20.7 mpg. The Alliance of Automobile Manufacturers, joined by the California Chamber of Commerce, the United Auto Workers, auto dealers and others, says the latest effort is a back door attempt to require more fuel-efficient vehicles. In a series of ads scheduled to run in newspapers, magazines and on radio beginning April 23, the auto industry and supporters suggest the Air Resources Board would consider raising gas taxes, impose a tax on the number of miles people drive or add fees on vehicles that consume higher levels of gasoline. With California accounting for more than 10 percent of U.S. vehicle sales, automakers fear the proposal would drive up prices and costs.