DETROIT  The cash-for-clunkers program turned out to be a boon for Asian automakers and the small cars they specialize in.

While American government officials hailed the monthlong program, which ended this week, as an overall stimulus to the economy, the biggest winner was Toyota, which accounted for 19 percent of all sales and had two of the top three best-selling models.

The Transportation Department said Wednesday that participants in the clunkers program bought 690,000 new vehicles. About $2.9 billion of the program’s $3 billion was distributed in government vouchers, which were worth $3,500 to $4,500 toward new-car purchases.

Detroit’s three automakers  General Motors, Ford and Chrysler  accounted for 38.6 percent of the vehicles sold. That figure is substantially less than the 45 percent combined market share that the Detroit companies posted in the first seven months of the year.