In this paper, a novel controller, the fractional order $PD^{mu}$ controller, is designed to improve the performance of the driver-vehicle system. First, fractional calculus and fractional order $PI^{lambda}D^{mu}$ controller are introduced. A control algorithm for vehicle directional control using the fractional order $PD^{mu}$ controller is then presented. Based on preview-follower theory, the on-line tuning method of the fractional order $PD^{mu}$ controller is designed. By comparing simulated and experimental results, the validity and robustness of the proposed fractional order $PD^{mu}$ controller in the closed loop system are verified. Finally, comprehensive evaluations are performed between the systems with the fractional order $PD^{mu}$ controller and with an integer PD controller. The results demonstrate that the use of the fractional order controller leads to an improvement of the performance of the driver-vehicle system.