Umm... what about this solution: instead of replacing the battery pack when it dies... remove it along with the electric motor and install a normal starter for the car. The reduced weight will make up for the loss of electric power. you'll still get a bazillion miles to the moon.

How much do the electric motor and battery pack weigh? With those units the car weighs, what, 1950lbs? So unless they are very light, taking out the electric motor and battery would be a very significant weight reduction for the car. And since the electric motor only produces 7hp, your weight to horsepower ratio will probably actually increase instead of decrease. Of course you'll have way less torque. Not sure how that will effect performance or if the gear ratios and transmission can handle that. Scary thing is, would this reveal the hybrid system to be a bunch of marketing hoo-haa? Has anyone done this to an insight?