So has anybody calculated what it will cost to charge the batteries on the Volt? Say you drove it enough to where you had to charge it every night. What would it add dollar-wise to your electric bill? A gasoline fuel efficient car can get 35-45 mpg of gas, and lets say current gas prices are $2.75 / gallon. What kind of mileage can be expected from the Volt for $2.75 worth of electricity to charge it?