The Australian Design Rules (ADRs) have set standards for occupant protection in private and commercial vehicles since 1968. In order to measure the impact of these design changes, the crashworthiness of vehicles manufactured from 1970 to 1995 was estimated from records of crashes occurring in Western Australia between 1987 and 1996. These crash records included crash site and driver information as well as the year of manufacture and the make, model and mass of each vehicle involved.

The risk of serious injury (hospital admission or death) in tow away crashes was estimated using multiple logistic regression. Adjustments were made for driver age, gender, speed zone, vehicle mass and mass ratio. Admission to hospital or death was derived from police crash reports that were linked to hospital discharge or death records in the WA Road Injury Database.

The median mass of crashed vehicles decreased from 1300 kg in 1970 vehicles to 1100 kg in 1985 vehicles and increased again to 1300 kg in 1995 vehicles. There were reductions in the proportion of drivers with serious injury over vehicle manufacture years 1970 to 1980. The estimated risk of serious injury to drivers of 1980s passenger cars was approximately two-thirds the risk for 1970s vehicles in most crash situations. However, there was virtually no improvement in crashworthiness of vehicles manufactured after 1990, when corrected for vehicle mass.