Thanks for the feedback so far but I do have a question for jakobnev
Quote:
Originally Posted by jakobnev
The force acting on the car is the same, but since speed is 50% grater in one example you need 50% more power! (P=V*F)
But the energy is the same, it's simply force times distance: W=F*D
So it's all down to what power lets the engine reach the better position on it's BSFC-chart.
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jakobnev:
For the P=V*F formula, shouldn't the speed V be considered as the effective air speed not the ground speed. Here's my logic with this. So if you had a 50 mph tail wind and this helped sustain the car along at 30 mph without any engine power, and you then turned on the engine and just pushed the gas pedal ever so slightly to sustain 30.1 mph would it be incorrect to write this as P=30.1*F ?, would it be more correct to have something like P=0.1*F, with most of the power likely overcoming the rolling resistance (F). I suspect operators of chassis dynamometers would know a thing or two about the mpg at various speeds with the absence of air drag.