This paper tackles the challenge of designing a polytopic switched unknown input interval observer for uncertain switched linear parameter varying (LPV) systems characterized by unknown yet bounded uncertainties and disturbances. The proposed solution introduces a switched unknown input interval observer (SUIIO) designed to estimate the lower and upper bounds of system states while remaining unaffected by unknown input disturbances. To establish the viability of such observers, the paper formulates sufficient Linear Matrix Inequalities (LMIs) conditions. These conditions are obtained using Multiple Input-to-State-Stable (ISS) parameter-dependent Lyapunov functions integrated with average dwell time (ADT). The efficacy of the proposed methodology is scrutinized through an evaluation of its performance in estimating lateral vehicle dynamics. This evaluation is conducted using Matlab-Simulink, providing a comprehensive assessment of the approach's practicality and applicability in the context of lateral vehicle dynamics estimation.