This report develops earlier research into statistical methods for comparing the secondary safety of car models, and investigates: (i) the likely effects on driver casualties in two-car accidents of downsizing (i.e. a Government-directed move towards lighter cars); (ii) three issues left unresolved by the earlier report. It is found that accident severity tends to increase with the combined mass of two colliding cars. A mathematical model of the effects of downsizing is developed from this relationship; results from this model suggest that downsizing would lead to fewer casualties in two-car accidents. Car models of similar mass can provide significantly different levels of protection to their occupants, so there would be fewer casualties if all models were to provide the same level of protection as the most successful current designs. It is estimated that if the safety of all models were improved to the level achieved or exceeded by the safest twentieth of models then the number of drivers injured would fall by 12 per cent and the number killed or seriously injured by 22 per cent. (A)
Abstract