I bought my 2011 volt in March 2011. I have always been able to get 34-40 miles on a charge. Now I am only getting 26 miles on a charge I brought it in to the dealer and they charged me $ 200 diagnostic fee and said there is no a problem and handed me a stack of how to drive the Volt. I have been driving it for 7 years so I think I know how to drive it. There has to be a reason it has dropped miles. It is hot here in southern Arizona so it is not the cold and I am not using the AC.