Four of the five top-selling cars in the government's "Cash for Clunkers" program are made by foreign automakers, according to new data released Tuesday by federal transportation officials.

The trade-in program has proved so popular that the government is in danger of running out of money for the rebates; Senate leaders said they plan to schedule a vote this week to boost funding.

Transportation Secretary Ray LaHood said 157,000 trades had occurred as of Tuesday morning, eating up $664 million of the $1 billion appropriated for the effort.

More than 80 percent of the vehicles turned in were trucks and sport-utility vehicles, the government said. The top-selling new car is the Ford Focus, followed by the Toyota Corolla, Honda Civic, Toyota Prius and...