Think of it as getting the most bang for your buck. When I buy something, I like to think I'm getting the most value for the money I am spending. That means I expect at least 90 to 100% return on the money I put in. Traditional automobiles with internal combustion engines are notoriously inefficient, losing most of the energy from the combustion process in the form of heat energy. If you have ever popped the hood to check your engine after you have driven your car, you can feel the tremendous amount of heat coming off the engine. Depending on the fuel consumption rate of the car, the return from the investment of fuel is very low. I used to drive a Honda 125 motorcycle when I was younger, that had a 3.5 gallon tank. I could fill that tank and drive that vehicle aggressively for 3 weeks before I had to fill it again! But that engine, despite its stingy consumption of gasoline, still had the majority of the energy being dissipated as heat energy. So I tend to view it as money being thrown to the wind, so to speak. It would be nice if we could develop a vehicle that had a higher efficency rating than that which currently exists.