The DS transmissions have been continuously developed in consultation with Colin Chapman: The 5 DS10 was expanded as the 5 DS12 (120 Nm) and most recently as the 5 DS20. Jim Clark won the legendary Indianapolis 500-mile race in 1965 with the Type 38 and a ZF 5 DS 20, in which the Newton meter figure had already been increased to 200. Jim Clark and Colin Chapman, in gentlemanly fashion, immediately thanked ZF by telegram afterwards, both congratulating ZF on the victory and expressing their enthusiasm for the constructors' achievement. A great gesture, which on the one hand certainly paid tribute to the high engineering skills of the ZF technicians - but on the other hand also reflected the congenial, charming manner of the congratulators and their close, trusting relationship with the designers at Lake Constance.
Although the connection between ZF and Lotus was very much one of partnership, in business terms it lasted until the end of the 1960s. The tragic events of 1968 with the loss of Jim Clark and Mike Spence certainly shocked ZF employees and in some way slowed down the previously highly praised commitment of the engineers.