The Green Car Journal chose the Volt from five finalists Thursday at the Los Angeles Auto Show.
The award was the latest for the Volt, which runs on electricity for 40 miles before a backup gas engine kicks in. Motor Trend also named the Volt its 2011 car of the year.
Separately, GM's Chevrolet brand said Thursday it's donating $40 million to environmental projects that reduce carbon dioxide emissions. Chevrolet aims to reduce 8 million metric tons of emissions. That's the same amount of emissions that the 1.9 million Chevrolet products sold in 2011 will produce in a year.
The announcements came as GM returned to public trading Thursday on the New York Stock Exchange.