Research on adaptive cruise control (ACC) is presently one of the most important topics in the field of Intelligent Transportation Systems. The main feature of such controllers is that there is adaptation to a user-preset speed and, if necessary, speed reduction to keep a safe distance from the vehicle ahead in the same lane of the road. Adaptive Cruise Control (ACC) operates in Velocity control mode and Distance control mode. ACC acts like a conventional Cruise Controller in the case of velocity control mode. This system has been designed using Fuzzy logic Controller. The inputs of the Fuzzy logic Controller are Distance error and the Speed Error. The output of the Fuzzy logic controller is acceleration or braking. 25 rules have been generated using Fuzzy Logic Controller with the knowledge base of the system The host vehicle adapts to the lead vehicle, but with a slow response. In order to fasten up the response (decrease the response time),Genetic Algorithm is used. Optimization of Fuzzy rule base is done by using the Genetic Algorithm The result shows better improvement over the Fuzzy logic Controller.