1. The engine :
        - has a good efficiency (30 - 40 %) only with a load near the maximum load.
        - need energy to maintain its movement (struggle against the brake motor)
 

2. Freewheel
       
Moving a vehicle coasting is always the most energy efficient
(like a bicycle).

 

 Driving with the less energy is obtained by a succession of :

- frank accelerations to gain kinetic energy with the best engine efficiency,

- followed by driving in neutral with a stopped engine, taking advantage of terrain elevation.
 

 

The car is not designed for this type of driving

 

Driving with the lesser energy for a car.