Safety is nowadays an increasingly important issue for automotive manufacturers. Plastic components, asides from its aesthetic function in the car interior, are required to act as passive safety components. In this work, the impact of an anthropomorphic mass with a given mass and velocity in a plastic pillar cover is simulated by a finite element code (ABAQUS/Explicit). The pillar is modelled as a solid discretised by 3D solid elements. The material’s properties (polypropylene) used in the pillar are obtained at high strain-rates and described by an elasto-plastic model, being adopted a maximum allowable strain failure criterion. The contact between the mass, the plastic component and the steel chassis are considered. A complete deceleration-time plot is obtained, being calculated the values of the Head Injury Criteria (HIC(d)) and maximum deceleration. The deformed geometry, resultant stress distribution and damaged zones are also predicted. The properties of the material (elastic modulus, yield stress and allowable strain level) are optimised, making extensive use of numerical simulations and a design of experiments approach, in order to meet the envisaged standards requirements and thus mitigating occupant injuries.