Occupant compartment designs and restraint systems are both of central importance in reducing occupant deaths and injuries. Motor vehicle compartments should be designed to minimize the likelihood of occupant ejection, occupant compartment intrusion, and occupant impacts with hostile structures inside the compartment.

Restraints reduce but do not eliminate the likelihood of such impacts. In all crash modes, both unrestrained and restrained occupants can and often do have violent impacts with rigid structures inside the occupant compartment. The designs of some interior features are required to meet the performance requirements of a number of Federal Motor Vehicle Safety Standards (FMVSSs). This paper focuses on the designs of interior features, such as instrument panels and front seat backs, likely to be impacted in frontal crashes, and considers the extent to which they are subject to FMVSS No. 201. The need to design such interior compartment structures to reduce injuries is especially important for children.

FMVSS No. 201 is inadequate. Based primarily on likely head impact areas of lap belted adult passengers, it applies only to parts of the top of the instrument panel ahead of center and right front passengers;​ very limited parts of the top of the backs of front seats without adjustable head restraints, or the center point on the tops and backs of adjustable head restraints;​ and sun visors, arm rests, and some interior storage compartment doors. Studies have indicated that very few occupant contacts in crashes occur in these areas. The standard is almost totally inadequate for drivers and, ironically, is probably even more inadequate for infants and children than for adult passengers, as there are virtually no protection requirements for vehicle structures directly in front of their heads and faces.

The standard presently in force is a much weakened version of the original standard issued January 31, 1967, which was intended to provide initial, minimum requirements for interior impact protection. The original January 31, 1967 standard itself was weaker than the 1966 proposal it was based on, which included requirements for unrestrained child impact areas. In 1970, an amended standard that dealt comprehensively with interior impact protection was proposed, but has never been implemented.

Although the principles of designing interior compartments that reduce the likelihood of injury from mechanical energy transfers are well known, many automobile manufacturers have chosen not to provide such designs. There are many examples of design features in current car models that increase injury potential, such as metal edges, rigid surfaces, hard protrusions and inadequate padding that are routinely found in likely impact areas not covered by FMVSS No. 201. However, some automobile manufacturers have placed more emphasis on injury reduction principles in the design of interior vehicle compartments, illustrating that such designs are practicable and can be accomplished without the loss of eye appeal or functional convenience. FMVSS No. 201 should be upgraded to force use of far less hazardous designs.