By promising to trim hundreds or thousands of dollars in interest costs over the span of a car loan, zero percent financing deals have made auto sales one of the economy's few bright spots since Sept. 11, according to the New York Times.

Cars and trucks sold at an annual rate of 21.3 million in October, the industry's strongest month ever. But many of those buyers ended up with loans that charged interest, and some may have agreed to higher prices than they would have under other buyer-incentive plans.

For consumers, the challenge is figuring out which models are covered, and whether the

deals apply to leftover 2001 models, to new 2002 models, or to both, according to the Times.

Dealers say they are trying to move metal at competitive prices. "You have to remember that we're not the only Chevy dealer in our town," said Bob Serpentini, who owns five Chevrolet dealerships in the Cleveland area. "People still shop. You still have to be competitive in the marketplace." Serpentini's dealerships sold 850 vehicles last month, compared with an average of 400 in previous Octobers.

While it's still unclear exactly how many buyers are getting zero percent financing, some dealers say it is only a quarter of the people walking in the door, and neither General Motors nor Ford would disclose what percentage of their recent sales were financed interest-free.