A 2012 Chevrolet Volt is featured at a dealership in the south Denver suburb of Englewood, Colo. Sales of the Volt set a monthly record of 2,800 in August, mostly due to steep discounts. (Associated Press)

A 2012 Chevrolet Volt is featured at a dealership in the south Denver suburb of Englewood, Colo. Sales of the Volt set a monthly record of 2,800 in August, mostly due to steep discounts. (Associated Press)