Crash data from real-life frontal car collisions, where the crash pulses have been measured with crash pulse recorders and where the influence of pulse shape on the risk of both short- and long-term disability from AIS1 neck injuries, have been studied. The risk of long-term consequences was especially influenced by the shape of the crash pulse. To understand how the shape of the crash pulse affected occupant motion, a series of computer simulations of frontal impacts were conducted where the information from the crash pulse recorder data has been used in the simulations. Several dummy response parameters, such as neck loads and accelerations, were compared with the injuries in 143 real-life collisions using the recorded crash pulses and the injury records. The results showed that for a specific change of velocity the pulse shape could significantly influence some of the dummy response parameters, such as angular head acceleration and neck bending moments. It was also found that there was a correlation between these dummy response parameters and the long-term consequences. The results may help to explain the injury mechanism of the AIS1 neck injury in frontal impacts and may have implications on the design of the seat belt system.