Abstract: A method of controlling a power unit of a vehicle, comprising a stage of calculating the theoretical increment/decrement (Ge, Gd) in the gear number required to pass from the actual operating condition of the vehicle to a condition of maximum power and, respectively, of maximum economy, and a stage of calculating the increment/decrement in the gear number required to obtain the optimum gear by means of an average of the theoretical increments/decrements (Ge, Gd) weighted with weighting factors (Ke, Kd) calculated on the basis of operating parameters of the vehicle detected by means of onboard sensors.