"Green vehicles like the Chevrolet Volt and Toyota Prius aren't really all about saving money on gas, but you would like to think that buying one would save you some cash in the long run.However, a true 235 MPG concept car does exist - The Volkswagen 1-litre Diesel Car.
We've crunched the numbers on various hybrids over the years and the result is usually the same -- it takes years to make up for the added cost of a hybrid compared to gas-powered vehicle of the same type." - Edmunds
Even At 230MPG, Volt Would Still Cost More To Own Than Prius (Edmunds)
Nissan claims 367 mpg for its electric Leaf - even though it doesn't use gas (USA Today)
EPA Won’t Confirm The Volt Gets 230 MPG (Wired)
Questions Surround GM's 230 mpg Chevy Volt Claim (U.S. News and World Report)