Why, Because their are millions of cars on the roads now. I am thinking of the short term. Not practical to think we could get all cars electric within 20 years.

To make all cars electric and cost efficient you would still need to build many nuclear power plants and if you had them you might as well power industry and homes to.

I do like the idea of electric cars but don't know if they would be any more earth friendly with out new battery technology and cheap electric power.