[RedDevil]

Originally Posted by IamIan

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.

Wow. First, joule is a measure of energy in itself. A certain mass moving at a certain speed has energy in the form of momentum that can be expressed in joules.
Raising the speed means increasing the momentum and needs additional energy.
Lowering the speed releases energy. The friction with the air, tires and mechanical parts generates heat. That friction is always there when moving, but when coasting there are no other forces involved.
The energy you have to invest to accelerate is gained back when coasting as the engine would have to run when maintaining speed.
Changing speed does not change the total amount of energy, just the state of that energy.

Tire RPM is just a function of speed and tire size, should not matter much and there is not much you can change about the size anyway unless you adapt the speedo.
The relation between RPM on the engine and the speed is what matters. Changing the final drive is way easier than changing the gearbox in most cases