The study of human behavior during driving is of primary importance for the improvement of drivers' security. This study is complex because of numerous situations in which the driver may be involved. In this paper, we propose a hierarchical fuzzy system for human in a driver-vehicle-environment system to model takeover by different drivers. The driver's behavior is affected by the environment. We include climate, road and car conditions in a fuzzy mode. For obtaining fuzzy rules, we have provided three separate questionnaires on the effects of climate; road and car condition on driver's performance. The number of fuzzy rules is optimized by Particle Swarm Optimization algorithm. Also the precision, age and driving individuality are used to model the driver's behavior under difference environments. We investigate the behavior of different drivers when a driver intends to pass the leading car. The comparative study showed that the simulation result is in good agreemen...