Passenger protection to reduce fatality and injury rates is of critical importance worldwide. Side and head impact occupant protection requirements have been legislated both in North America and Europe. Even though the applicable legislation for each impact condition is different, the impact event poses similar functional requirements. Therefore, concept designs and methodologies for engineering optimization can be used interchangeably to develop countermeasures whether dealing with side or head impact crashworthy systems.The present paper outlines the use of a systematic approach that combines structural CAE simulations and Design of Experiments (DOE) for the optimization of the structural performance of crushable thermoplastic energy absorbers that are being used in door panels and upper interior trim. The use of DOE allows the evaluation of critical design and material parameters which affect the performance of the system. For interior components, these parameters include material properties such as modulus, yield strength and plastic strain limit, and geometric factors such as absorber shape, thickness distribution, rib depth and rib spacing. Emphasis is placed in showing the dependence of absorber performance on these parameters to demonstrate the application of this technique to the design environment. This process not only saves development time and costs but also helps understand the overall performance behavior of the system under impact loading conditions.