(August 8, 2009) President Obama signed into law Friday morning legislation infusing the "cash-for-clunkers" with another $2 billion in hopes of extending a wave of trade-in deals that buoyed car sales and boosted demand for fuel-efficient vehicles in late July.

The Senate passed the bill Thursday, 60 to 37. The House already had approved putting $2 billion more into the program, which gives consumers up to $4,500 in federal subsidies for trading in cars that get less than 18 mpg and buying new cars with better fuel economy.

Obama welcomed the extension of the "cash for clunkers" incentive, saying it would aid economic recovery and help the troubled auto industry. The law extends the program until Labor Day, the first Monday in September, and prevents the two-week-old incentives from running out.

Some skeptics say the additional money won't have the same impact as the first $1 billion, because many people who qualified for the program already have bought new cars and the supply of eligible vehicles is waning.