The Citroen SM may have begun as early as 1961 as a desire to produce an upmarket sporting Citroen DS. However, the reality had to await the acquisition of Maserati and the availability of a suitable engine. The 2670cc V6 used in the SM was derived from the Maserati V8 by Giulio Alfieri having common components and being able to be produced on the same production line. The engine later went into Maserati's Merak which was a Bora adapted to the 1970s recession. In the SM the engine was hooked up to sophisticated hydraulics including suspension, brakes, and for the first time variable power steering. The whole package was wrapped in an aerodynamic sports coupe with kamm tail by Robert Opron, and launched at the Geneva Salon in 1970. Production started later in 1970 but was ended in 1975 after only 12000 because of the post 1973 oil crisis recession; the take over of Citroen by Peugeot in 1974 is also a likely reason for the demise of the SM.