1975: Hot-dip galvanised body
In 1975, Porsche responded to the issue of corrosion with emphatic success. The 911 was the first series production car to be given a body that was hot-dip galvanised on both sides – allowing Porsche to offer a six-year corrosion guarantee, which was extended to seven years for the 1981 model year and then later to as much as ten years. The treated body-in-white not only improved the service life but also vehicle safety, as the process preserved the overall rigidity and the crash safety characteristics of the body, despite vehicle ageing. It played a part in the reputation of the 911 as being an extremely durable vehicle – two thirds of all the 911 cars ever built are still licensed for road use today. Extensive tests were carried out before the body was launched for series production. This included trials with stainless steel as the body material – three shiny silver prototypes were made from this material, one of which can be seen today at the Deutsches Museum in Munich. However, the engineers decided not to use stainless steel but rather to galvanise the body-in-white, as this was easier to produce. Driving the prototypes through a bath of salty water to test resistance to corrosion is a legendary part of the test course in Weissach.