Has anyone besides me done the arithmetic on claims for the soon-to-be-new Chevy Volt? It's an electric car with a back up 53KW gasoline-powered charging system--you plug it in to a power line at night and it's supposed to have a range of some 40 miles without recharging. After 40 miles, the engine starts up and recharges the batteries.

Now, the chhrging system is a 53 KW generator. It it were 100% efficient, it would require an eighty or so hp gas engine to run it.
And, once you've passed that initial 40 miles, you're effectively running the car on the gas engine, with a generator and electric motor acting as intermediaries. How in hell does that get the claimed 230 mpg? Or have I made a mistake somewhere?