Ideal drive for cars

For an ideal drive system with 100% efficiency, only air resistance and rolling resistance has to be calculated

Energy for acceleration does not count

At the energy balance of an ideal drive system, the energy for acceleration and for driving uphill has not to be accounted. The car will not drive always the same speed or park only on a mountain. When the car stops after each trip at the same position, the energy effort for acceleration is compensated with the energy gain by braking. The energy effort from driving uphill is compensated by the energy gain by driving downhill.

Glowing disk brakes are 0% efficiency

When a drive system converts all the energy gain from braking only in glowing disk brakes, than this system has at energy recuperation only 0% efficiency.

Fossile cara have a terrible bad efficiency in city traffic

Calculating only rolling and air resistance, an 1,8 t vehicle with 0.01 rolling resitance, 2.8m² front area and cw=0.34 uses at 50km/h only 8,12 kWh/100km. Sometimes 60, sometimes 30, sometimes stoping, but in average 50km/h. With a modern Diesel engine is the consumption 8,6 l/100km. 86 kWh chemical energy converted into 8.12 kWh mechanical energy. 9.4% efficiency.

This can be much worse. A luxury car with huge gasoline engine can have less than 5% efficiency in city traffic.

Searching a parking lot

When Your car has a consumption display, make an experiment. Reset the consumption display before entering an underground parking area. A minivan can uses here about 5 kWh/100km, but the consumption display states 12,5 l/100km. 4% efficiency. Big gasoline cars reach there even below 2%.