The effects of vehicle impact speeds, door stiffness and occupant spacing with respect to the impacted door surface on occupant collision speeds were investigated in simulated lateral impacts using the MVMA-2D model. The study matrix included 10, 20 and 30 mph AV collisions; 2, 4 and 6 inch occupant to door spacings; and two side structures of different stiffness characteristics. The data showed that the control of whole door stiffness is more effective in achieving reduced occupant impact velocities than occupant spacing or the attempts to limit the intrusions at either the upper or lower portions of the door. The study also showed that the height of the predominant intrusion controls the direction of occupant rotation and that increased lateral vehicle stiffness results in lower residual occupant velocities.