Originally posted by: vegetation
It basically isn't cheaper in the long run. It would take a LONG time to save $4000 in gas costs. If you compare the Prius to the Corolla and assume that the Corolla gets 40 mpg and the Prius gets 60 mpg, then it would take years to save $4000 in gas costs. If you really want to save money on a car, buy a used car with low insurance costs.
Don't forget you'll need a new battery pack once you hit so many miles and nobody knows how much this will really cost at this point. But considering it's pretty much a dealer-only type of job, you're at their mercy.
actually, you can buy the battery packs at your toyota parts counter for about $4000, IIRC. they are actually pretty easy to install