Presumably they would make gains in efficiency, but only to a point - if a gallon of gasoline contains 34 kWh of energy you'll always need at least that much to

Presumably they would make gains in efficiency, but only to a point - if a gallon of gasoline contains 34 kWh of energy you'll always need at least that much to create one, and at 60 kWh/gal now they aren't that far off.