<p>This paper proposes an adaptive fixed-time sliding mode control (AFTSMC) strategy for addressing the problem of vehicle platoon control with heterogeneous model structures under unknown disturbances. Firstly, a sliding mode surface is designed to ensure the convergence of the spacing error within a fixed-time after the convergence of the sliding mode surface. Next, the constant time headway policy is employed and the string stability is ensured by introducing the coupled sliding mode surface based on the bidirectional topology. Furthermore, to mitigate the chattering issue caused by the sign function, a smoother sliding mode reaching law with adaptive parameters is adopted. Through Lyapunov stability analysis, it is proven that the AFTSMC strategy guarantees the stability of individual vehicles. Finally, the effectiveness and superiority of the proposed control scheme are validated through simulations.</p>