The Chevrolet Malibu was named the 2008 North American Car of the Year. Mazda's CX-9 sports utility vehicle was named truck of the year.
"The Japanese have owned this segment for over a decade, but Chevrolet's shot across their bow suggests the terms of surrender have, at long last, been violated," one of the judges, Karl Brauer of industry tracking website Edmunds.com, said of the Malibu.
The awards, which carmakers typically use to market their vehicles, were awarded by a panel of 45 automotive journalists and presented at the North American International Auto Show in Detroit.
GM won both car and truck honours at the 2007 show and had a chance to repeat this year. The number one US carmaker had four of the six finalists in both categories.
Trailing the Malibu (190 points) were GM's Cadillac CTS (165) and the Honda Accord (95). The Mazda SUV finished with 201 votes, topping GM's Chevrolet Tahoe Hybrid (140) and Buick Enclave (109).
Last year, GM's Saturn Aura won the car award, while the Chevy Silverado pickup won truck honors. This year was the 15th year for the awards.