This Paper reports on a sample of nearly 3700 accident-involved cars with 4491 injured occupants. These were selected from a comprehensive crash-injury investigation which has been underway in the UK since 1983. Detailed injury mechanisms quantify injury sources from this very large sample and enables a perspective view to be taken on future direction of remedial measures. The results show that the majority of impacts were to the front of the vehicle and involved the offside part of the front more often than the nearside. Approximately three quarters of the front occupants were known to be restrained, while most of the rear seat passengers were unrestrained. As expected, the unrestrained passenger sustained a greater level of overall injury than the restrained, this difference being more pronounced in side impacts. In absolute numbers, most injuries occurred to the cranium and limbs with the steering wheel being responsible for most head/face and trunk injuries to the driver. Most of the other injuries to all occupants occurred when they contacted adjacent, internal structures in the direction of impact. The seat belt webbing featured highly in trunk injuries and although these are seen as a lesser evil than injuries sustained by the unrestrained. A proportion of upper body injuries were caused by contact with another vehicle or external structure and it is reasoned that attention should be given to reducing injuries from intrusion in side impacts. The results indicate that all occupants should be restrained. Means such as persuasion or enforcement should be used to make restraint use effective. Consideration must also be given reducing entrapment, particularly of the lower limbs, in order to improve the clinical outcome of casualties who may have other injuries.