We have a Yaris based car in Thailand and its rear coil springs at least are pigtailed. It has done 120k kilometres, no problems, and some of the potholes in rural Thailand need to be seen to be believed. But, of course, Thailand never freezes so the roads are never salted so springs never corrode and fracture from road salt. However, suspension and tyre damage caused by speed humps and speed cushions urgently needs to be properly investigated. How many spring failures and how many blowouts from worn inner shoulders of tyres have caused fatal crashes? I estimate around 500 fatalities a year. On 22nd May Boris Johnson was nearly wiped out on his bicycle when the back door of a truck unlatched on a speed hump, hit a car, and dragged it across the road. (Footage at www.liveleak.com/view?i=416_1243123434)