Since chemical agents with a small amount could kill a lot of people, quick detection must be done first. In this study, the optimal operation speed for efficiency of CBR patrol car was investigated with experiments which were carried out to find reasonable speed of the vehicle by using IMS sensor and subsonic wind tunnel. As a parameter for the experiment, velocity of wind was considered to describe a situation a car runs, and the sensitivity of IMS sensor was measured by the oscilloscope analysis. As a result, through experimentation and analysis, it was possible to derive the optimum operation speed at which the sensor could recognize the chemical agents.