FACTORS ASSOCIATED WITH SAFETY OF PASSENGER CARS

In the United States, an analysis has shown that tighter fuel efficiency requirements that leads to lighter vehicle bodies would cause an increase in the number of fatal accidents. However, other recent work argues that fuel economy is not relevant to the occurrence rate of fatal accidents. This research is aimed at examining the relationship between vehicle characteristics including fuel economy and the occurrence rate of accidents in Japan. Traditionally, the safety of passenger cars has been assessed through the use of laboratory data from the viewpoint of risk of death and injury under the assumption that accidents have already occurred and results have been published in New Car Assessment. On the other hand, we examined safety from the perspective of the occurrence rate of accidents resulting in death (fatal accidents) and accidents resulting in injury or death (hereinafter “accidents”). We conducted negative binominal regression analyses of the occurrence rates of fatal accidents and accidents, taking into consideration the influence of driver-related factors, and vehicle characteristics. The results of our analysis demonstrate that there was no important difference in the adjusted occurrence rates of fatal accidents and accidents, which excluded the effects of driver-related characteristics, among vehicle types other than minivans and sport and specialty cars. In addition, the adjusted occurrence rate of fatal accidents was not strongly correlated with the score in New Car Assessment. While the adjusted occurrence rate of fatal accidents exhibited a tendency to decrease inversely with the increase in the weight of the vehicle, we obtained an opposite result for sport and specialty cars, which have an adjusted high occurrence rate of fatal accidents. There is the possibility that the interior volume or the vehicle shape has a greater influence on the occurrence rate of fatal accidents.