Rotary-Powered Unicorn: 1973 Citroen GS Birotor

Just under 900 examples built

Citroen was known for adopting peculiar technical and design solutions for many of its cars, but we bet you didn’t know the company used a Wankel rotary engine in one of its mid-1970s GS models. The project, while interesting, turned out to be a major flop, with only just under 900 units being sold between 1973 and 1975.

It failed because it was noticeably more expensive than lesser engined variants – by up to 70 per cent – which made it nearly as expensive as the larger and more luxurious DS.

As its name suggests, the GS Birotor used a twin-rotor Wankel setup that displaced 1-liter and made 107 hp and 140 Nm. With the car being under 1 ton in weight, it gave nippy acceleration (0-100 km/h in 14 seconds) and a more-than-respectable top speed of 175 km/h or 109 mph – its sprint capability was hampered by the choice of gearbox: a three-speed semi-automatic unit that according to period records was quite jerky.

Performance was not the source of its downfall, though – it was the atrocious fuel consumption: the car guzzled even up to 20 l/100 km and this ended up making it quite unpopular.