This paper focuses on the lateral control of intelligent vehicles; the aim is to minimize the lateral displacement of the autonomous vehicle with respect to a given reference path. The control input is the steering angle and the output is the lateral displacement error. We present the design and validation of a robust lateral controller based on the Immersion and Invariance (I&I) principle in order to ensure robust stability and good performances with respect to parametric variations and uncertainties that are encountered in driving applications. To validate our control law, tests were performed on SCANeR Studio, a driving simulation engine, according to several real driving scenarios. Simulations were also performed using experimental data acquired by the DYNA vehicle (a Peugeot 308) belonging to the Heudiasyc laboratory. The validation demonstrates the robustness and good performances of the proposed control approach and clearly shows the improvement due to the I&I controller.