Driving assistance device for a motor vehicle, said device further comprising a gearbox ratio sensor, and in which a driving assistance module is capable of detecting a condition for entering a driving assistance method, the entry condition comprising a gearbox ratio condition, the gearbox ratio condition being met when the gearbox ratio is equal to a predetermined gearbox ratio selected from the first gear ratio and the second gear ratio of the gearbox, the vehicle further comprising an engine control unit capable of: - computing a vehicle speed setpoint (41, 43, 95) as a function of an acceleration setpoint depending on a distance to a target as a function of time and of a current speed of the vehicle; - computing a vehicle dynamics management torque setpoint (50, 54, 56) as a function of the vehicle speed setpoint, of the current speed of the vehicle and of a current torque of the powertrain; - computing a gearbox input torque setpoint as a function of the engaged gearbox ratio and of the vehicle dynamics management torque setpoint; - regulating the engine speed as a function of the gearbox input torque setpoint; and - computing a clutch torque setpoint as a function of the gearbox input torque setpoint and of the clutch status, the vehicle further comprising a clutch control unit capable of regulating a physical quantity controlling the torque that can be transferred by the clutch as a function of the clutch torque setpoint, the driving assistance device further comprising a road grade sensor, the driving assistance module being further configured to determine a road grade, characterized in that the predetermined gearbox ratio is the second gear ratio in response to a negative or zero road grade and the first gear ratio in response to a positive road grade. the vehicle further comprising an engine control unit capable of: - computing a vehicle speed setpoint (41, 43, 95) as a function of an acceleration setpoint depending on a distance to a target as a function of time and of a current speed of the vehicle; - computing a vehicle dynamics management torque setpoint (50, 54, 56) as a function of the vehicle speed setpoint, of the current speed of the vehicle and of a current torque of the powertrain; - computing a gearbox input torque setpoint as a function of the engaged gearbox ratio and of the vehicle dynamics management torque setpoint; - regulating the engine speed as a function of the gearbox input torque setpoint; and - computing a clutch torque setpoint as a function of the gearbox input torque setpoint and of the clutch status, - computing a vehicle speed setpoint (41, 43, 95) as a function of an acceleration setpoint depending on a distance to a target as a function of time and of a current speed of the vehicle; - computing a vehicle dynamics management torque setpoint (50, 54, 56) as a function of the vehicle speed setpoint, of the current speed of the vehicle and of a current torque of the powertrain; - computing a gearbox input torque setpoint as a function of the engaged gearbox ratio and of the vehicle dynamics management torque setpoint; - regulating the engine speed as a function of the gearbox input torque setpoint; and - computing a clutch torque setpoint as a function of the gearbox input torque setpoint and of the clutch status, the vehicle further comprising a clutch control unit capable of regulating a physical quantity controlling the torque that can be transferred by the clutch as a function of the clutch torque setpoint, the driving assistance device further comprising a road grade sensor, the driving assistance module being further configured to determine a road grade, characterized in that the predetermined gearbox ratio is the second gear ratio in response to a negative or zero road grade and the first gear ratio in response to a positive road grade.