As an example, let's make a trial calculation under the following conditions.It is a simulation of a gasoline engine car of almost Axela class, running at a constant speed of 40km / h on a flat road.

・ Rolling resistance coefficient = 0.015 (general asphalt pavement) ・ Vehicle weight = 1,345 kg
・ Crew weight = 55kg ・ Cd value = 0.33 ・ Air density = [1.2kg / m3] ・ Front projected area = 2.2m2 ・ Travel speed = 40,000m / 3,600s (40km / h)
・ Gradient (θ) = 0 ・ Car acceleration = 0m / s2
・ Equivalent inertia weight (force converted from engine to drive wheel to acceleration. In the case of 2WD, about 3% of vehicle weight) = 40kg

First of all, since the efficiency of the motor system is unknown, we will set the fuel consumption rate to 20km / L for the time being and calculate the efficiency. Since I ran 1km in 20L, the efficiency of the prime mover system = 20,000 N / 33,000,000.

Loss energy (J) = N x 20,000 (m) = Supply energy (J) = 33,000,000 (J / L) x1L x Motor system efficiency

If you keep calculating, the answer will be 15.73%.It may be surprisingly low, but since it also includes the efficiency of the drive system, it will change depending on the driving situation, but for gasoline engine cars, it is almost at this level.Most of it is decided by the basic design, so unless it is a full-scale race specification, the degree of change is small, for better or worse, with the tuning of the intake and exhaust system.