On Wednesday, May 28, 2014 8:43:05 PM UTC-4, jim wrote:

You can buy a diesel that uses

40% of the fuels energy, but the best any gasoline

engine can deliver is 25% efficiency.


Wiki disagrees and says gasoline engines can deliver 30% efficentcy.

http://en.wikipedia.org/wiki/Engine_efficiency

Modern gasoline engines have a maximum thermal efficiency of about 25% to 30% when used to power a car. In other words, even when the engine is operating at its point of maximum thermal efficiency, of the total heat energy released by the gasoline consumed, about 70-75% is rejected as heat without being turned into useful work, i.e. turning the crankshaft.[1] Approximately half of this rejected heat is carried away by the exhaust gases, and half passes through the cylinder walls or cylinder head into the engine cooling system, and is passed to the atmosphere via the cooling system radiator.[2] Some of the work generated is also lost as friction, noise, air turbulence, and work used to turn engine equipment and appliances such as water and oil pumps and the electrical generator, leaving only about 25-30% of the energy released by the fuel consumed available to move the vehicle.

Dan