Momentum is building in Washington to force automakers to markedly improve the fuel efficiency of their vehicles -- a requirement that could cost them billions of dollars by forcing them to produce smaller cars and more hybrids, or even drop out of some market segments.

President Bush proposed in his State of the Union address that automakers improve the efficiency of vehicles an average of 4 percent per year beginning in 2009 for passenger cars and 2011 for light trucks. Bush wants to cut gas consumption 20 percent by 2017.

The costs involved would be huge considering that modest light truck standards issued in March requiring fuel efficiency improvements of just 1.2 percent per year will cost the Big Three automakers an estimated $6.2 billion. Nearly all the foreign and domestic automakers have called the Bush proposal very aggressive.

Several proposals in Congress would go even further, mandating a specific yearly increase, while the Bush proposal leaves the final increase to the National Highway Traffic Safety Administration, which would set the new figure with input from automakers. More at Detroit News