The gas engine is the power source if you drive over 40 miles without recharging. That's te key concept behind the Volt. You aren't limited by the battery and its recharge time. You could drive the Volt for 100 days straight, only stopping to refill the gas tank, just like any other car.
you _could_ drive it like any other car, but you don't HAVE to. That's the point of the volt.
The leaf is not a hybrid, the volt is. Seems pretty simple here folks.
The volt is not a hybrid - it's fully electric.
"Gort, klaatu nikto barada." -- The Day the Earth Stood Still