In this paper, a set of longitudinal velocity and distance controllers with switching logic is proposed for an active driver safety system, and validation via hardware-in-the-loop simulation (HILS) is presented. Since the desired velocity and distance are given discretely and arbitrarily by a driver, there are usually discontinuities or discrete jumps between the desired and current vehicle state immediately after the switching. To minimize performance degradation resulting from this discrete jump, dynamic surface control (DSC) with an input-shaping filter is applied for both velocity and distance control. Furthermore, while much cost and effort are usually necessary for the experimental validation of a longitudinal controller, the validation of the longitudinal controller via HILS is performed with a minimum of effort. In the HILS, the various switching scenarios and desired discrete inputs in terms of velocity and distance are considered and the corresponding performance of the controller is shown in the end.