There are many things that General Motors has been incredibly forthcoming about as they’ve developed the Volt for all the world to see. Certainly no other vehicle has been the subject of so many videos and webchats detailing its trips through 2 feet of water or its visits to the arctic or some other form of vehicle torture.

But when it comes to the Volt’s real-world fuel efficiency, GM has methodically avoided comment. Now, thanks to the keen eyes of some web denizens, it appears that one video shot by a Volt test driver shows that the Volt achieves less than 30 mpg after the battery has been depleted—in what’s called charge-sustaining mode. Given that the Prius is capable of obtaining 50 mpg on average, the revelation is rather shocking.

(more…)