Sure they cut the gas bill to next to nothing, but electricity is not free no matter how one slices that.
No the electricity to charge those vehicles isn't free, a couple of dollars for a full charge approximately .
What is the cost of replacing batteries?
Thats the unknown catch, for these batteries usually poop out after numerous charges and wear and tear 10 to 15+ years and they are extremely expensive to replace.
One shouldn't expect to buy these cars on the thinking they are going to last 20 years with the same original battery .
I would assume that once auto manufacturers really ramp up production of electric driven vehicles there would be an expanding aftermarket battery replacement industry.