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GS (GZ) Birotor

1973 - 1975

Original publicity material Interior, exterior and dimensions
1973 article from le Double Chevron 33 Owner's handbook
A Birotor in Britain
1974 British brochure 1974 technical specification
1975 French brochure 1973 press release
1973 Midi Auto Moto review

A total of 847 GZ Birotors were built between 1973 and 1975. Initial trials were undertaken using a NSU and then the M 35. NSU employed the Wankel engine in the stunning Ro 80 with Rolls Royce and Mazda also investigating the engine's possibilities. It was rumoured that the CX would be fitted with this engine - indeed surprise was expressed at the time that the Birotor was not fitted to a top of the range model but to the mid range GS .

Powered by a rotary engine invented by Felix Wankel and built by Comobil, later Comotor, a joint venture between CitroŽn and NSU, the car was not without its problems - high fuel consumption, high pollution, high oil consumption and lack of reliability all served to kill the project. NSU was absorbed by Audi and the Wankel engine was dropped by European motor manufacturers. Mazda in Japan persevered however and the RX series of sports cars still make use of the rotary engine.

How the Wankel rotary engine works


Twin chamber Wankel rotary, 1990 cc, 107 bhp DIN @ 6500 rpm, 11 CV French fiscal rating, water cooled, Bosch electronic ignition, twin choke Solex carburettor


Front wheel drive via 3 speed semi automatic gearbox


Rack and pinion


Powered discs all round


Hydropneumatic , self levelling, independent featuring anti dive/anti squat geometry


Michelin XAS 165 HR 14


Modified GS saloon with flared wheel arches


Length : 4.12 m, width : 1.64 m
Fuel consumption 13 litres per 100 km
Top speed 175 kph
Fuel tank capacity 56 litres
Click to see high resolution image
Click to see high resolution image
Click to see high resolution image

The CitrŲen GS Birotor: Prodigy to Pariah
by David Milloy

birotor14.jpg birotor17.jpg