It's more efficient too, gotta love having both.
If Tesla has taught the automotive world anything, it's that if you're going to build a niche vehicle, you might as well go all the way with it. Just a few years ago, it was predicted that the whole country would be in an electric car buying frenzy by now. Given this clearly has yet come to fruition, it seems that carmakers are changing their strategy to make the cars less compromising. A logical move, especially if mainstream success isn't going to happen anyway.
So the Volt is becoming more powerful, in both its electric and gasoline power plants. We're hoping for upgraded interiors as well, but for now, enjoy the video about the mechanics of the car.