From NYTimes.com: Tracking Down Auto Warranty Callers

On Sunday, Senator Charles E. Schumer held a news conference to complain about car warranty telemarketing calls.

Mr. Schumer said he had received several of these warranty renewal robo calls -- the latest taking place last Wednesday.

"I've had enough," Mr. Schumer said. "These are scam artists."

I haven't received one of these calls but I know a lot of people who have.  But, now that politicians are annoyed things will probably get done to stop them.

UPDATE 5/15/09
NYTimes.com: F.T.C. Cracks Down on Car-Warranty Robocalls

The seller took in more than $10 million as a result of the calls, as well as related mailings, according to the commission.

Scams work, that's why they do them until they're caught.