Dylan Smith wrote:
It doesn't matter how much - energy will be lost in the process.

Of course it will, but don't neglect conversion
efficiencies and alternative energy sources.

The net efficiency of converting crude oil to gasoline,
distribution down to the individual car at a few gallons
at a time then to locomotion via the piston
engine/transmission/drive train is very poor.

In a fuel cell system, various materials including crude
oil, natural gas, etc. would be converted to hydrogen in
bulk then distributed with less evaporation loss and
converted to locomotion with fuel cell/electric motors
that have a much higher conversion efficiency than the
piston engine/transmission/drive train


Soup to nuts the net conversion of BTU's to mechanical
energy would be better. No violation of thermodynamics,
just modern engineering.

Neither crude oil nor natural gas have to be involved at
all. Solar panels or nucler reactors can supply the
energy to crack water directly.

Finally has been good progress on the Direct Methanol Fuel
Cell which has the advantage of using a low pressure
liquid in the car.