Speaking in very round numbers, let’s say my gasoline-powered vehicle gets 25 mpg, and the gas costs $4/gallon. That makes it cost $16 to drive 100 miles.
Now let’s say my electric car can go 100 miles on a full charge. How much electricity does it take to charge the car, and how much does that electricity cost?
You have to tell us something about the capacity of the batteries in your electric car, and the cost of electricity in your location. It will probably come out looking pretty cheap, but given current technologies, you REALLY have to figure in the depreciation of the batteries, which have a limited lifetime, and aren’t cheap.
This Wikipedia article is a good place to start:
sqweels - Thanks!