Inertia
*Drawing from Theory of ground vehicles, 2^{nd} ed., J.Y. Wong, 1993, p. 169 (modified)
Theory (more)
Theory
Vehicle mass (more)
Knowing the engine size (V_{eng}) in liters, the vehicle mass (m_{v}) can be estimated with equation (1):

(1) 
Where C_{m} depends on the vehicle type, as in the following table:
Vehicle type  C_{m} 
Race car  0.32 
Motorcycle  0.35 
Race car (production model)  0.55 
Sport car (2seat)  0.85 
Passenger car  1.00 
Luxury car  1.10 
Mass factor (more)
The mass factor (λ_{m}) is the relationship between the total mass of the vehicle (m_{v}) and the effective mass (m_{e}) of the vehicle, if we take into account the effect of the inertia of the rotating parts on the vehicle acceleration characteristics, such that:

(2) 
Where F_{net} is the net thrust acting on the vehicle and a is its acceleration.
From Theory of ground vehicles (2^{nd} ed., p. 211), for passenger cars, an empirical relationship can relate the mass factor with the overall gear ratio (G):

(3) 