In rear impact crashes, seats provide basic occupant restraint. Using 11 years of NHTSA's NASS CDS data (1997-2007), the performance of first row standard and integrated restraint seats were compiled and contrasted to each other and also to belt restraint performance in frontal crashes. This paper defines integrated restraint (IR) seats as those where the shoulder belt anchor is attached to the seat back frame instead of the vehicle body. IR seats have strengthened frames designed to support the frontal crash belt loads. NHTSA data indicates that more than 500 make/model/model year vehicles have an occupant position with an integrated restraint seat. In this study, vehicles with IR seats were identified using NHTSA data and confirmed by individual photographic review.

The median Delta V value for occupants in rear impact crashes was about 20 kph (12 mph);​ the same as for occupants in frontal crashes. In rear crashes, standard seats deformed or failed (per NHTSA coding) 25% of the time. In frontal crashes, seat belts (which comprise the basic frontal restraint system) failed 0.36% of the time (rate 69 times lower). The median Delta V for all reported seat failures and deformations was 27 kph (16.2 mph). Occupants reached MAIS= 3 (at least one serious injury) at half the Delta V level in rear crashes (19 kph) compared to belted occupants in frontal crashes (38 kph).

The maximum Abbreviated Injury Scale (MAIS) levels were also compiled for integrated versus standard seats. No occupant in an IR seat in a rear crash reached more than MAIS= 1. 50% of all occupants in rear crashes in standard (non-IR) seats experienced injury(s) resulting in MAIS=3 by a Delta V of 19 kph. IR seats were found to significantly reduce the rate of injury (MAIS>0) in rear impact crashes compared to standard seats (p=.05).