M35 Wankel engined coupé 

The Wankel rotary engine was viewed as the engine of the future.
Citroën had great plans for this technology. It was intended to be used in a range of cars - the single rotor in a cheap car, a birotor in a mid range car and a trirotor in a top of the range car.
In the event, only the M35 and GS Birotor were built in small numbers.