The Citroën SM is a high-performance coupé produced by the French manufacturer Citroën from 1970 to 1975. The SM placed third in the 1971 European Car of the Year contest, trailing its stablemate Citroën GS, and won the 1972 Motor Trend Car of the Year award in the U.S. History. In 1961, Citroën began work on 'Project S' – a sports variant of the Citroën DS. As was customary for the firm, many running concept vehicles were developed, increasingly complex and upmarket from the DS.
https://en.wikipedia.org/wiki/Citro%C3%ABn_SM