This paper presents an intelligent on-line route guide system using leader-following concept in a fleet. In order to achieve the concept of a car leader leading other car members in a fleet, we establish their contact through the real-time GPS position data with a 3G wireless communication. Every car members can obtain the real-time positions of the leader car and other car members. Then, the corresponding following route can be computed and shown by a client device in the car. Finally, a dynamic and real-time following function in a motorcade is achieved. The experimental results are provided to verify the reliability and the real-time function of this proposed concept. The most impressive advantage is that the proposed concept can provide more convenience in driving and can be easily extended to other applications such as a stolen-car searching system, a dynamic public bus regulation system, a collision prevention system, etc.