Citroën

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. At some stage in the 9-year project, it evolved from developing a faster variant of the DS to developing an entirely new, thoroughly engineered car. The result was the Citroën SM, first shown at the Geneva Motor Show in March 1970. After purchasing Maserati in 1968, Citroën had access to that company's famed engine technology which resulted in a 2,670cc V6 Maserati engine under the SM bonnet. The SM was unusually aerodynamic for its era, designed in-house by Citroën's chief designer Robert Opron. Unfortunately, the car suffered from a variety of maintenance issues. Many engines experienced failure at 60,000 km and required expensive, specialist care due to their unique design. Almost 13,000 cars have been made in five years time.