This paper describes a novel concept of driver assistance system that can give timely advice on safe and efficient driving. From both the current traffic condition obtained from sensory data and the driver's goal and preference in driving, it autonomously generates advice and gives it to the driver. Not only operational level advice, such as emergency braking due to an abrupt deceleration of the front vehicle, but also tactical level advice, such as lane changing due to the congested situation ahead, can be generated. Two main components of the intelligent navigator, the advice generation system and the road scene recognition system, are explained. On-line experiments using the prototype system show the potential feasibility of the proposed concept.