The U.S. Senate on Wednesday is expected to extend a program giving people government rebates when they trade in their old gas-guzzlers. But some auto dealers in the Chicago area say they’re having a hard time keeping up with demand.

ambi: Sound of car starting

That’s the sound of a 2009 Ford Focus. And Maureen Joyce says it won’t be around for long.

JOYCE: I will be out of Focuses, I would say, this month.

Joyce owns a dealership in the South Loop.

She says Focus sales have quadrupled, thanks to the so-called “cash for clunkers” program.

It’s been such a hit with consumers that Congress may allocate another $2 billion to keep it running. The Focus has been the top-selling car for the program.

But Joyce says Ford has slowed production for the summer - and that’s come back to bite her.

JOYCE: I am worried [about] where more cars are. I need more cars.

She says even if she orders more now, they wouldn’t arrive until after Labor Day - when the “cash for clunkers” money is expected to run dry.