Quote:
Originally Posted by tinduck
I have yet to see a car which uses less fuel when cruising at higher RPM. Internal engine friction and pumping losses wil see to that!
|
This is more or less true, but, there may be cases where you are getting down close to lugging with your foot into it, where going a gear lower results in getting the engine up into a more efficient rpm range. I believe this is particularly true with diesels where the pumping loss advantage of having a wide open throttle is not a factor, but having it floored results in a much richer mixture. I had this explained to me by an old OTR driver with a few million miles of driving diesel trucks over mountain passes.