The Federal Motor Vehicle Safety Standard (FMVSS) 216, "Roof Crush Resistance," specifies a roof testing method that requires cars to have a roof strength of at least 5,000 lbs. or 1.5 times the vehicle weight. This study evaluates the effect of vehicle roof strength (as measured in FMVSS 216) on severe occupant injury using police-reported motor vehicle accident data from Florida, Texas, Michigan, and North Carolina. The study also evaluates the effect of vehicle shape as measured by the overall height-to-track width ratio on severe occupant injury in rollovers. The validity of the state data was verified using NASS matched case data.

The data was controlled for accident severity, restraint use, and driver demographics. Based on 60,758 single vehicle rollover accidents in the four states, the following conclusions were reached:​

• There is no relationship between vehicle roof strengthto-weight ratio and the likelihood of severe injury for the vehicles studied. This conclusion holds for both non-ejected and ejected occupants.
• There is no relationship between the roof strength-tovehicle-weight ratio and the likelihood of severe roof damage for vehicles involved in rollovers.
• There is a strong relationship between vehicle shape and severe roof damage for vehicles involved in rollovers. High vehicles like vans have less roof damage than low sports car type vehicles.
• There is a weak relationship between vehicle shape and severe occupant injury. High vehicles have slightly fewer severe injuries in rollovers.