A method of determining at least one energy efficiency indicator of a path of a vehicle, said path corresponding to a motion of said vehicle between two successive stops of said vehicle, comprising the following steps: a) measuring the instant speed (V mes) of the vehicle over said path, b) identifying at least one waypoint of said path for which said instant speed has been modified according to conditions external to said path, said waypoint being determined: - by determining local minima of said speed (V mes) over a path, or - by means of a geolocation device that lists the road signs, the road configuration and the traffic, or - according to the condition of the brake system of the vehicle, or - by means of communications established between said vehicle and the vehicles in the immediate surroundings thereof, or communications established between said vehicle and the traffic lights, c) decomposing said path into at least one sub-path, each sub-path being defined between two successive waypoints, and determining for each sub-path a distance and an average speed of said sub-path by means of said measured instant speed (V mes), and d) determining, as the first energy efficiency indicator, an optimal speed (V opt) of said path, said optimal speed (V opt) being calculated for each sub-path by means of an optimization algorithm that determines a speed minimizing the energy consumption of the vehicle, said algorithm being constrained by the instant speeds at said waypoints, by said distance and by said average speed of said sub-path: said optimization algorithm determining an optimal speed (V opt) for each sub-path by passing through said identified waypoints, said waypoints defining the initial speed and the final speed of each sub-path, and by means of said average speed determined for said sub-path. a) measuring the instant speed (V mes) of the vehicle over said path, b) identifying at least one waypoint of said path for which said instant speed has been modified according to conditions external to said path, said waypoint being determined: - by determining local minima of said speed (V mes) over a path, or - by means of a geolocation device that lists the road signs, the road configuration and the traffic, or - according to the condition of the brake system of the vehicle, or - by means of communications established between said vehicle and the vehicles in the immediate surroundings thereof, or communications established between said vehicle and the traffic lights, - by determining local minima of said speed (V mes) over a path, or - by means of a geolocation device that lists the road signs, the road configuration and the traffic, or - according to the condition of the brake system of the vehicle, or - by means of communications established between said vehicle and the vehicles in the immediate surroundings thereof, or communications established between said vehicle and the traffic lights, c) decomposing said path into at least one sub-path, each sub-path being defined between two successive waypoints, and determining for each sub-path a distance and an average speed of said sub-path by means of said measured instant speed (V mes), and d) determining, as the first energy efficiency indicator, an optimal speed (V opt) of said path, said optimal speed (V opt) being calculated for each sub-path by means of an optimization algorithm that determines a speed minimizing the energy consumption of the vehicle, said algorithm being constrained by the instant speeds at said waypoints, by said distance and by said average speed of said sub-path: said optimization algorithm determining an optimal speed (V opt) for each sub-path by passing through said identified waypoints, said waypoints defining the initial speed and the final speed of each sub-path, and by means of said average speed determined for said sub-path.