DETROIT -- General Motors says its money-back guarantee is going so well, it will extend the program through December, according to The Associated Press.

The automaker launched its "May the Best Car Win" campaign in September as a way get consumers to try GM cars and trucks with minimal risk.

The program was slated to last 60 days and end Nov. 30. It will now last until Jan. 4, 2010.

The campaign includes advertisements comparing GM vehicles to those of competitors.