WASHINGTON (AP) -- The Cash for Clunkers program, as expected, has been a boon for carmakers -- especially those in Japan and South Korea.

Government data shows that while 54 percent of the top-10-selling vehicles were manufactured domestically, eight out of 10 carry Japanese or South Korean nameplates. The Toyota Corolla is the most popular car bought under the program. Only the Ford Focus and the Ford Escape cracked the top 10.

American automakers are dominating one area -- trade-ins. All the top trade-ins were made by U.S. companies, with the Ford Explorer four-wheel-drive leading the pack.

The government data show that fuel economy of vehicles bought under Cash for Clunkers is now 25 miles per gallon, while the mileage of trade-ins stands at 15.8 miles per gallon.

Meanwhile, dealers across the country are reporting that reimbursement issues continue to stall the wildly popular incentives program. They have submitted requests for rebates on 338,659 vehicles sold, at a cost of about $1.4 billion to the government, according to sales data summarized by Transportation Department officials.

David Wilson, a Toyota dealer in Orange County, Calif., told Automotive News that he has been paid for only three of 92 claims he submitted before Aug. 2, leaving him on the hook for about $374,000. In total, he has 450 unpaid claims filed for $1.9 million.

"I'm worried the government will run out of money before we get paid," he told the publication.