Detailed investigation of over 1,100 accidents, representative of all injury severities, has shown that car occupants who were wearing seat belts sustained substantially fewer than those who were not. Seat belts reduce injuries by restraining the wearer, so reducing the likelihood of violent contact with the vehicle interior and by preventing ejection from the vehicle. Where injuries to belt wearers did occur, the main problem was still occupant to vehicle contact, exacerbated by distorted parts of the vehicle intruding into the passenger compartment, rather than direct seat belt loading. A comparison between automatic and static lap and diagonal seat belts showed that overall, both performed equally well in alleviating injury, but thare was an indication that automatic belts were more likely to be worn than static ones