The self‐protection standards of the vehicle fleet were hypothesized to have decreased as a function of manufacturing year. The hypothesis was tested using GIDAS data from 2000‐2015, for both the belted and unbelted populations. Occupant injury was assessed using an iteration of the New Injury Severity Score, the NISSx. Injury rates were described by point estimates and were plotted against vehicle manufacturing year. Vehicle mileage was considered an exposure measure when determining injury rates. For a given sample of injured occupants, the greatest decrease in injury rate was associated with a NISSx>1 (MAIS2+) injury. The reason for the strong reduction to this injury severity was attributable to the mitigation of 1≤NISSx<2.5 injuries. Logistic regression models were developed to identify factors that have caused this injury mitigation. Euro NCAP compliancy and a deployed frontal airbag for the belted population had significantly reduced effects of mitigating injury. Results also indicated the rate of 2.5≤NISSx<5 injuries has remained constant. Future development of vehicle platforms should consider safety measures to mitigate injuries of these severities.