By applying some advanced features of the CAL3D occupant simulation model, a single model incorporating the vehicle structure and a simplified occupant was developed for studying the sensitivity of occupant response to parameter changes in perpendicular, vehicle-to-vehicle side impacts, not involving vehicle rotation. The results of the model show qualitative agreement with published experimental results, which indicate that occupant responses are related to the initial clearance of the occupant from the door, the stiffnesses of the front end of the impacting vehicle, and the side structure of the impacted vehicle.