According to the U.S. Department of Transportation, National Highway Traffic Safety Administration (NHTSA) and the Insurance Institute for Highway Safety (IIHS), side-impact car accidents are the second leading cause of fatalities in the United States. Compared to all other accidents, side-impact crashes are quite dangerous to the occupants because of their limited ability to absorb the crash energy and less space for intrusion. NHTSA and IIHS have developed safety standards to prevent fatalities by conducting several experiments using anthropomorphic test dummies (ATDs). Although the regulations are based on the use of crash dummies, there might be differences between actual human crash performance and dummy crash performance. In recent years, technology has improved in such a way that crash scenarios can be modeled in various computational software, and human dynamic responses can be studied using active human body models, which are a combination of rigid bodies, finite elements, and kinematic joints, thus making them flexible to use in all crash test scenarios. In this research, nearside occupants were considered because they are more likely to be injured in a side-impact crash. Vehicle side-impact crash simulations were carried out using LS-DYNA finite element (FE) software, and the occupant response simulations were conducted with Mathematical Dynamic Models (MADYMO) software. Because the simulation of an entire FE model of a car and occupant is quite time consuming and expensive, a prescribed structural motion (PSM) technique was utilized and applied to the side-door panel with an occupant positioned in the driver seat of the car using the MADYMO code. Regular side-impact deformable barrier and pole test simulations were performed with belted and unbelted occupant models considering two different target vehicles—a mid-size sedan and a small compact car. Responses from dummy and human body models were compared in order to quantify the noticeable differences between the two performances in nearside-impact accidents.