There are four modes to the Chevy Volt system. There has been much discussion as to whether the Volt is an electric vehicle, a hybrid or something else.
The Volt has a 16 Kw hour battery. We start with converting DC to AC in the electric traction drive. There is a 1.4-liter engine that holds 9.3 gallons of premium gasoline.
Here is animation of the 2011 Chevy Volt and all four of its modes. If you are a geek you will love this animation.
According to Chevy the Volt can drive up to 100 mph pure EV, at around 3:30.
If you are looking for the place where they talk about the 4th mode it’s around 3:50.
At around 4:10 they start talking about converting from a one-motor to a two-motor driving.