One car has been returned under General Motors' unconventional 60-day return policy--a Chevrolet Corvette.

The reason? A customer grew tired of shifting with the manual gearbox, GM vice chairman Bob Lutz said on Wednesday. The Vette was exchanged for one equipped with an automatic transmission.

Recounting the story for journalists at a luncheon event in Detroit, Lutz said it's the only “authenticated” incident of a car being returned under GM's new program, which offers the challenge, “May the Best Car Win.”

Lutz said: “He brought it back because he made a mistake.”

The risky, money-back guarantee is part of the company's goal to be more aggressive in taking its message to consumers. Lutz pointed to an advertisement that shows Chevrolets registering better fuel-economy figures than counterparts from Toyota.

“We can stand the comparison with just about anybody,” Lutz said. “[But] we need to close this perceptual gap.”

The GM vice chairman, who switched from product boss to the company's honcho for marketing, advertising, and communications, said the message is resonating with consumers. He says consideration for GM vehicles is up 15 percent and says its market share in September, 20.5 percent, is the same as last year.