Quote:
Originally Posted by RedDevil
...but it does make clear why pulse and glide works.
Short bursts of power using the engine efficiently combined with long coasts with the engine off instead of running the engine all the time, wasting fuel on pumping losses from having the throttle all but closed.
The alternative is having a final drive ratio that allows for low RPM as highway speed and an engine that runs efficiently at those low revs. The lower the revs, the higher the load on the engine and the efficiency.
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Pulse and glide on the ICE ... to avoid running at low efficiency conditions ... yes.
Not so about the vehicle speed itself changing.
The two are in competition ... changing vehicle speed will always need more joules of energy than a steady state vehicle traveling at the same average speed , for the same distance , and same conditions... that is always a negative of Vehicle P&G.
Sometimes the additional joules of P&G vehicle are countered by enough increase in ICE P&G efficiency ... sometimes not ... like many things it depends on the specifics.
Another alternative ... instead of an ICE that can work as you describe ... would be an efficient transmission that compensates for the difference between Tire RPM and Load vs ideal ICE RPM and load.