The first part of this investigation is concerned with the results of the autopsies of 70 passengers. The material has been gathered from head-on collisions involving passenger cars of various types, where no safety belts were used.

The injury mechanisms are divided into six typical groups according to the parts of the vehicles struck by the passengers.

It appeared that the most important factors deciding the type of injury mechanism were the construction of the engine hood, the windshield and frame, the instrument panel and the seat, not considering intruding objects and parts of other vehicles which may cause injuries.

The second part of this investigation has as its objective the corroboration of these observations in sled tests of head-on collisions using dummies;​ the results obtained are measured as forces acting in the head, the chest, and the thighs. In addition, the movement of the occupants is studied when the design of the instrument panel is changed.