GM has designed a car which can drive 40miles on only battery power, and indefinitely (as long as the gas lasts) on generator power. And this car will cost something like $40,000, and will probably be a big money loser, according to the Obama automotive task force.
Why is GM shooting for the moon? Why not reduce the battery to something small, enough for maybe 5 or 10 miles pure electric driving? And instead of running the engine only when the batteries are depleted, run the engine more frequently to maintain a high level of charge. Then, use the batteries for accelerating and low speed driving, and use the engine more often during cruising.
Perhaps the generator could even be a high compression ethanol only design, to eke out more efficiency.
They'd get big fuel economy numbers (but not 230 mpg), and a much less expensive car. It would have nice torque, because it would be electrically driven, unlike the Prius.