Officially titled the Car Allowance Rebate System (CARS), the program offers rebates of up to $4,500 for vehicle trade-ins used to purchase new cars with improved fuel efficiency.
Before it adjourned, the House approved a $2 billion expansion of the program that ran through its $1 billion budget in the first week.
Democratic senators seized on a Department of Transportation report that the first 120,000 applications were for cars rated at 28.3 miles per gallon, The New York Times reported Tuesday.
"It's working as a stimulus. It's working to help families. It's working to improve mileage," said Sen. Charles Schumer, D-N.Y.
White House spokesman Robert Gibbs said, "it's good for our energy security and our environment."
But some Republicans were grumbling. Senate Republican leader Mitch McConnell of Kentucky said the budget-breaking flood of applications showed the program was badly managed.
Automakers reported mixed results. Ford Motor Co. said sales increased 2.3 percent in July from a year ago -- the first increase in two years. Chrysler Group and General Motors Co. reported sales slipped in July, down 9 percent and 19 percent, respectively.
Copyright 2009 by United Press International.