Despite a good prognosis for individual victims, AIS 1 neck injuries causing long-term consequences are the most common disability injury in Sweden. This study compares the characteristics of rear impacts causing both short- and long-term disability neck injuries. Real life data from Swedish insurance material during 1990-1993 were used, where the resultant impact injuries to the neck were divided into two groups: occupants reporting initial symptoms shortly after the crash and a subgroup were the initial symptoms later developed into a long-term disability (chronic symptoms at least 1 year after the impact). The influence of change of velocity, crash pulse of the struck car, and the risk of long-term disability to the neck in different car models, were evaluated. The relative risk of neck injury in terms of initial disability was strongly influenced by the mass ratio between the struck and the striking car while other parameters such as crash pulse were an influencing factor in crashes causing long-term disability. Also, there was a 2.7 times higher risk of sustaining a long-term disabling neck injury in a vehicle manufactured in the end of the 1980s or beginning of the 90s than in one manufactured in the beginning of 1980. If one of the main reasons for the increasing number of long-term disabling neck injuries is associated with the influence of crash-pulse and factors related to newer car models, the situation will gradually become worse as the older car fleet is replaced. There is an increasing need for effective preventive measures, based on long-term disability data.