<p>In an unprecedented federal attack on a California auto pollution program, the Bush administration backed carmakers Wednesday in a legal challenge to the state's requirements for increased sales of electric and low- polluting vehicles.</p>
<p>Justice Department lawyers filed papers with the U.S. Court of Appeals in San Francisco arguing that the state Air Resources Board's latest zero- emissions rules violate the federal government's exclusive authority to regulate fuel efficiency. The ARB rules do not dictate mileage-per-gallon standards but allow manufacturers to comply by selling a certain percentage of fuel-efficient hybrid vehicles that run on both gasoline and electricity.</p>