This paper investigates a prescribed tracking performance vehicular platoon control problem with actuator saturation, dynamics uncertainties, and unknown disturbances. First, a novel Gaussian error function (GEF)-based saturation function is introduced to approximate nonsmooth actuator saturation of each vehicle in a smooth way. Then, a fixed-time performance function (FPF) is proposed. Subsequently, an adaptive fixed-time sliding mode control scheme is developed based on the GEF and the FPF, which guarantees all signals of the closed-loop system are bounded and the tracking error converges to a predetermined region in fixed time. Meanwhile, string stability and traffic stability are also guaranteed. Finally, the effectiveness of the proposed algorithm is verified through numerical simulations.