In this paper, longitudinal automated vehicle control for platooning is investigated by both experiment and simulation. Two-car platooning is realized by controlling the throttle of the following car. A vehicle model which is used for simulation and as a control model for experiment is constructed. The model contains nonlinear elements of the engine, the torque converter and the automatic transmission. Comparison of sliding control(SC) and PID control(PID) is done under various conditions. It is shown that especially under large initial deviation from the target state sliding control has better stability and more rapid convergence than PID control.