It sure looks like any GS. But the Birotor is a complete package of advanced engineering: Rotary Combustion Engine (Wankel), semi-automatic gearbox and hydraulic suspension.
Whatever this is, it isn't an ordinary GS!
Take a closer look at this GS: you might notice the wider wheel arches, the different rims and hubcaps, and on the right side and trunk lid; the Birotor badge...
In 1967, Citroën and NSU joined forces in a company called Comotor. In fact, the NSU cooperation started off in 1964, when the Comobile company was created. This resulted in the hatching of the M35 in 1969, a Citroën AMI as 2+2, with a single rotor RCE and hydraulic suspension. Citroën eventually launched the Birotor in 1974. A few prototypes were made in 1973, but the main production started in March 1974. Up to the vacation period in August, 750 vehicles had been assembled. After the vacation, production rate was significantly lower, resulting in 93 cars more in '74 and only 31 built in '75. All in all, 874 Birotors were built. In 1977 Citroën recalled the model, and most cars were destroyed. Approximately 200-250 cars could be saved, unfortunately many of them without registration documents. An unknown number of those remaining cars have been re-registered, and are now legal for road use, even if one might suspect that the Birotors aren't frequently used. Most of the remaining cars are still in France, but one might find Birotors in Sweden, Netherlands, Germany, Denmark, England and Australia.
The powersource is a two chamber (two rotor) rotary combustion engine, hence the name "Birotor". It develops 107 hp SAE at 5500 rpm and 14 kgm at 3000 rpm in a chamber volume of 497,5 cc (equivalent to a piston engine of 1990 cc). The engine is radially fed by a Solex two port carburetor.
When the engine is running, the Birotor looks short and high, almost like a 4WD. Some of this appearance is due to the different sized wheels. Instead of the 15" rims on the ordinary GS, the Birotor received not only wider rims, but also a lesser diameter, 14", with a Michelin 165/14 XAS tire.
Citroën was implying luxury interior in the Birotor, and it has of course a more luxurious interior than an ordinary GS, but nothing really special. Nice, well padded interior though. Early models had vinyl door covering, while the model year 1975 received cloth door covering. On the dashboard a set of round dials surrounded by warning lamps is found. All these dials and lamps are mounted in a matte brushed aluminium plate. Available extras was radio, tinted glass and sunroof.
Follow my attempt to restore the 624 Comotor.