The Aura beat out the other two finalists for the car award, the Honda Fit (jazz) and the Toyota Camry. The Silverado bested the Ford Edge and the Mazda CX-7.
The winners were chosen by a jury of 49 motoring journalists in the United States and Canada. The results were announced at the Detroit Motor Show.
The recognition represents the latest sign of a possible turnaround at GM, which just a year ago faced daunting threats of bankruptcy, sliding market share, soaring costs and sharp outside pressure from a big-money shareholder.
GM management silenced some critics by cutting more than 34 000 jobs and unveiling plans to close 12 plants and reduce recurring costs by $9 billion. But many pointed out that delivering sustained profitability would require a strong product line as well as aggressive cost-cutting.
Although GM still sells twice as many cars in the US market as Toyota, it is on track to be overtaken by Toyota for the global top spot in terms of production in 2007.
Quality and innovation have been seen as areas where GM has lagged Toyota.
But GM is banking on a different image this year. It has several new car models hitting showrooms in 2007, including the Chevrolet Malibu, the Cadillac CTS and the Saturn Astra.
It also has well-reviewed crossovers - car-based utility vehicles that are smaller than its traditional SUVs - such as the GMC Acadia, Saturn Outlook and Buick Enclave.
The new Saturn Vue and Aura will also hit showrooms.
Angus Mackenzie, the editor of Motor Trend magazine, told Reuters on Sunday that the redesigned Malibu was "proof that GM design is back from the dead."