The driver safety arms race is phenomenon whereby car drivers are incentivized to buy larger auto-vehicles in order to protect themselves against other large auto-vehicles. [1] [2] [3] [4] This has a spiralling effect whereby cars get increasingly larger, which has adverse overall effects on traffic safety. [5] [6] It is an example of a prisoners' dilemma, as it can be individually rational to attain larger vehicles while having adverse outcomes on all traffic users. [7]