In system and method for improving operator driving assistance of an automotive vehicle, at an indication of acceleration timing and magnitude and the lane change timing, a lane change necessity is calculated and a lane change trigger signal is produced while the host vehicle is operated on a road that has at least three lanes and, at the calculation of the lane change necessity and at the production of the lane change signal, a new lane change trigger signal is prohibited to indicate until a forward lane change operation is deemed to be completed, in a case where the vehicle is traveling on a multiple number traffic lane road.