Based on the theories of linear quadratic regulator (LQR) control and linear matrix inequality (LMI), a scheme of discrete-time optimal preview position control algorithm for automotive electronic throttle control (ETC) system was proposed. The presented throttle valve position tracking control algorithm consisted of the state-feedback control, discrete integrator, and preview feed-forward control. The closed-loop controller was realized by only utilizing a low-cost sliding potentiometer which was used to measure the angle position of the throttle valve. To track the position of automotive electronic throttle valve, the discrete-time state space model was firstly established for the automotive ETC system. Then, the augmented error system which contained future position reference information was built by using the state transformation method instead of the traditional difference method, which helped to simplify the structure of the augmented error system. In simulations, the physical parameters uncertainty and external disturbance torque of the real automotive electronic throttle control system were also considered, and the simulation results were verified by bench tests for throttle through utilization of the rapid control prototyping (RCP) technology. Both simulation and test results demonstrated that the proposed discrete-time optimal preview position control algorithm was able to effectively improve the transient performance and robustness of the ETC system while guaranteeing the tracking accuracy. Hence, the application of the presented control scheme on the ETC system can further improve the fuel economy, dynamic and exhaust performance of gasoline engine.