TH-400 Turbo-Hydramatic. The new body was a typical General Motors style and bore a strong resemblance to the contemporary Holden Brougham from GM Australia. The Diplomat V-8 was hoped to compete with Mercedes' new 350 and 450 SE; from May 1973 Opel even offered a long-wheelbase version of the V-8 to keep up with Mercedes' SEL models. In October 1971 the Diplomat's list of standard features included H1 halogen headlamps, radio antenna integrated into the windscreen and remote-controlled rear view mirror. From January 1972 the 4-speed manual gear box was no longer offered on the Diplomat E. September 1972 saw the introduction of a modified grille with OPEL script relocated from its left side to its central portion. A number of the 'lesser' Admiral cars had their car boot lid fitted with Diplomat lettering/badges. This led to some confusion by today's car buyers, even in the TV series Der letzte Bulle (German), but the cars are easily identified by their vertical headlights for the Diplomat versus horizontal ones for the Admiral. Opel continued the production until 1977 but found little success in the market: only 61,559 KAD cars were built from March 1969 to late 1977 (of which 4,976 Kapitäns, about 33,000 Admirals and about 23,500 Diplomats). They were superseded in 1978 by the new Opel Senator of a somewhat reduced size and more modern, European styling. In the early 1970s, GM considered the use of Opel Diplomat as the basis of forthcoming first generation Cadillac Seville. However, the precise panel gap tolerance found in Diplomat was beyond what the GM North American manufacturing plants could do without extensive and expensive changes to the sheetmetal stamping and welding process. The Diplomat V8 furnished the technical base for the Bitter CD, a limited-production GT. The production of the handbuilt German car used the foolproof chassis, drivetrain, mechanicals, and even the dashboard of the Opel Diplomat. Bitter's enterprise of providing exotic car looks with Opel innards came to an end in the early eighties, when the Opel Diplomat chassis was no longer available to buy from Opel. References Werner Oswald, Deutsche Autos 1945-1975. Motorbuch Verlag, Stuttgart 1975. Diplomat Rear-wheel-drive vehicles Cars introduced in 1964 1970s cars