Tanstaafl (there ain't no such thing as a free lunch).
"Show me just what Mohammed brought that was new, and there you will find things only evil and inhuman, such as his command to spread by the sword the faith he preached." - Manuel II Palelologus
I got that kind of mileage from my Volkswagen Jetta diesel back in the 70's.
Now we're to have orgasms because an ultra expensive battery will push a lightweight car 40 miles and then the engine comes on to recharge the battery?
Something is missing from this scenario.
To GM: good luck selling these.