Identification method of the optimal gear (G TARGET) for a transmission of a vehicle provided with an engine; the identification method comprises the steps of: measuring a proceeding speed of the vehicle; measuring a current rotation speed (ω CURR) of the engine; determining a reference driving power (P REF); identifying the available gears (G AVA) which are able to make the engine provide the reference driving power (P REF) at the proceeding speed of the vehicle; calculating for each available gear (G AVA) the corresponding expected rotation speed (ω A), which would be imposed on the engine according to the proceeding speed of the vehicle and to a transmission ratio of the gear; calculating for each available gear (G AVA) the corresponding expected torque (T A), which would be required to the engine according to the reference driving power (P REF) and to the expected rotation speed (ω A); determining for each available gear (G AVA) the corresponding expected efficiency (E A) from the engine according to the expected rotation speed (ω A) and to the expected torque (T A); identifying a gear (G BEST) with the maximum efficiency among the available gears (G AVA) by identifying the gear presenting the highest expected efficiency (E A); identifying a current gear (G CURR) currently engaged; determining for the current gear (G CURR) the corresponding efficiency (E CURR) of the engine according to the current rotation speed (ω CURR) and to a current torque (T CURR) or a reference torque (T REF); determining an efficiency differential (ΔE) between the efficiency (E CURR) of the current gear (G CURR) and the expected efficiency (E A) of the gear (G BEST) with the maximum efficiency; and identifying the optimal gear (G TARGET) by choosing between the gear (G BEST) with the maximum efficiency and the current gear (G CURR) according to the efficiency differential (ΔE); the identification method is characterized in that it comprises the further steps of identifying the gear (G BEST) with the maximum efficiency as the optimal gear (G TARGET), only if the efficiency differential (ΔE) is higher than the first threshold value. measuring a proceeding speed of the vehicle; measuring a current rotation speed (ω CURR) of the engine; determining a reference driving power (P REF); identifying the available gears (G AVA) which are able to make the engine provide the reference driving power (P REF) at the proceeding speed of the vehicle; calculating for each available gear (G AVA) the corresponding expected rotation speed (ω A), which would be imposed on the engine according to the proceeding speed of the vehicle and to a transmission ratio of the gear; calculating for each available gear (G AVA) the corresponding expected torque (T A), which would be required to the engine according to the reference driving power (P REF) and to the expected rotation speed (ω A); determining for each available gear (G AVA) the corresponding expected efficiency (E A) from the engine according to the expected rotation speed (ω A) and to the expected torque (T A); identifying a gear (G BEST) with the maximum efficiency among the available gears (G AVA) by identifying the gear presenting the highest expected efficiency (E A); identifying a current gear (G CURR) currently engaged; determining for the current gear (G CURR) the corresponding efficiency (E CURR) of the engine according to the current rotation speed (ω CURR) and to a current torque (T CURR) or a reference torque (T REF); determining an efficiency differential (ΔE) between the efficiency (E CURR) of the current gear (G CURR) and the expected efficiency (E A) of the gear (G BEST) with the maximum efficiency; and identifying the optimal gear (G TARGET) by choosing between the gear (G BEST) with the maximum efficiency and the current gear (G CURR) according to the efficiency differential (ΔE); the identification method is characterized in that it comprises the further steps of identifying the gear (G BEST) with the maximum efficiency as the optimal gear (G TARGET), only if the efficiency differential (ΔE) is higher than the first threshold value.