Based on injuries determined by autopsies of 82 car drivers, who died after a straight head-on impact, and based on the deformation of the interior of the accident vehicles, the cause of the injuries was analyzed.

This material can be divided into four groups, the characteristics of which are mainly defined by location and design of steering assembly, instrument panel, and seat.

This evaluation led to a new explanation of the fatal aortic rupture at the classical site appearing very often, and to a number of conclusions relevant to the design of automobiles in terms of internal safety.

Tests performed on the impact sled with cadavers and using various steering assemblies at impact speeds of approximately 37 mph confirmed the explanation of the mechanism of the aortic rupture as well as the satisfactory performance of a steering assembly with a shock-absorbing device which latter proved to be especially effective in preventing severe thoracic injuries.