A few things, most of the power in gasoline is lost in heat. Think exhaust and cooling. I think its less than 20% is actually used to propel the car. Another ting is aerodynamics. Look at most of the present high milage cars and motor cycle contest. Some type of aerodynamic devices are used. Usually wheel pants or fairings and belly pans. Also, look at the Borque engine. And I disagree with that we are getting the most effieceintcy out of our fuel. There is still some work being done on fuel atomization.
Tom