As the traffic on roads becomes increasingly heavy, driving safety has widely become a concern. Thus, an advanced driving-assistance system (ADAS) becomes much more important, because it can improve driving safety. It is composed of a human driver and an automated system called a copilot. To make it effective, they should properly cooperate. Hence, it is very important to define and model their cooperation behavior such that an ADAS can effectively be designed and realized. This paper presents the colored hybrid Petri net (CHPN) model to describe their cooperation behavior. It shows how switch between the driver and the copilot should be done to control the vehicle. The model is shown to be deadlock-free and conflict-free. Therefore, it is useful for ADAS design, analysis, and simulation.