A 2012 Chevy Volt electric car is seen at the AltCar Expo in Santa Monica

 
A 2012 Chevy Volt electric car is seen at the AltCar Expo in Santa Monica
A 2012 Chevy Volt electric car is seen at the sixth annual Alternative Transportation Expo and Conference (AltCar) in Santa Monica, California September 29, 2011. REUTERS/Lucy Nicholson