I disagree. The Volt has a smaller engine, running at an optimal RPM, powering the car. It has one task. The 1.8L in the Prius is not only larger and older, it has multiple functions, and presumably more influenced by the driver's right foot. Additionally, the Volt has regenerative brakes and more efficient Li-ion batteries with a charge range wider than the 40 to 60% of the Prius. Volt is expected to be 300 to 400 lbs heavier than the Prius. Significant, but not enough so that I would write it off yet.

 

I also disagree. Remember that the Volt's gas engine is never powering the car.
It always runs on the battery power, which even though it will be regenerated by the small gas engine, still runs much more efficiently than if powered directly by a gas engine. If that makes any sense. In other words, it takes less power to regenerate a battery than it does to power a car itself. Therefore, the Volt could very well get better than 40 mpg in regeneration mode.

 

Plus, unless you're flogging it, the batteries are going to recharge through the generator and the regenerative brakes and when the batteries reach a preset charge level, the generator shuts down again. It's not like once the initial charge is gone the gas engine has to run until the car is plugged in again.