Citroën SM: Gallic thoroughbred?

Few things epitomise 1970s cool as effectively as the Citroën SM. Designed to be the company’s flagship with no expense spared, its overengineering ensured the SM packed the substance to match its style.

Produced from 1970-75 when it was canned by bean-counters as a loss-leader, the SM is probably best known for its heart: a Maserati V6 designed specifically for use in the space-age Citroën. The Italian company adapted one of its existing supercar V6s with a specially designed short-stroke crank and slightly reduced bore, providing a 2.7-litre capacity for the early cars. Featuring triple-Weber carburettors, the original engine produced a muscular 170bhp before Bosch injection was utilised and raised peak power to just under 180bhp. The final versions featured a 3-litre and were more commonly specified with a 3-speed automatic gearbox as opposed to the five-speed manual normally fitted.

In truth, the Maserati engine is merely the icing on the cake. The French fancy was loaded with technology carried over from its DS sibling, such as the swivelling, self-levelling headlights, hydropneumatics and brakes that ran from the same system. For the first time, these included discs all round as standard.

The SM was very nearly even more radical, as before an agreement was made with Maserati the French company had considered a triple-rotor Wankel rotary engine. A Birotor version of the popular and equally futuristic mid-size GS appeared in 1973, so it seems that Citroën eventually realised this particular experiment in a more compact package.

An idea for a go-faster DS was originally muted as early as 1961 and various design iterations were considered, developed and then shelved before the SM was born as a completely new design. The stunning Robert Opron-penned shape provided an incredible 0.26 drag coefficient in early wind tunnel tests, which makes the SM as slippery as the most efficient shapes 50 years later and enabled a clearly class-leading top speed of 138mph.

As a dynamic trailblazer, Citroën’s DIRAVI steering provided speed sensitive assistance and powerful self-centring that provides a unique driving perspective. With only two turns lock-to-lock, Citroën worked hard to give its outrageously comfy cruiser a sporting feel through the bends, which is a compromise that met with a mixed reaction from contemporary road-testers.

Latterly, the SM has finally received deserved recognition as an engineering and design marvel. The wondrously gruff engine note, famously floaty hydropneumatic ride and instantly recognisable lines make Citroën’s flagship the ultimate way to express your 70s appreciation in a truly iconic way.

Is there a greater way of celebrating the 70s?