This paper investigates the problem of robust state estimation and unknown input interval reconstruction for uncertain switched linear systems. Parameters uncertainty are supposed to be provided with known bounded compact set. A design method for obtaining interval observers that provide guaranteed lower and upper bounds of the state and unknown inputs is proposed. By adopting multiple quadratic ISS-Lyapunov function and average dwell time concept, new and less conservative stability conditions are derived, and a set of numerical feasible linear matrix inequalities (LMIs) are given. An application to vehicle lateral dynamics estimation is considered to show the effectiveness of the algorithms. Experimental data obtained with a prototype vehicle are used to confirm the performance of the proposed approach.