A design strategy to simultaneously address the interaction of two restraint systems (airbag and belt) and two test conditions (FMVSS 208 and NCAP) was investigated. This design strategy was implemented using a math-based methodology for a midsize car passenger side restraint system. A number of airbag and safety belt design variables were examined and optimized resulting in improved NCAP performance for the midsize car used in the simulations. The result of this study shows that this math-based methodology could be used to project the potential performance of restraint systems for future vehicle programs. As is the usual recommended procedure for math-based results of highly complex nonlinear mechanical analyses of the type under consideration herein, test validation should be carried out prior to implementation of specific results in a production program.