Following the 1969–1971 trial program for the innovative rotary-powered M35, the Citroën GS-based Birotor was powered by, as the name implies, a twin-chamber engine with design rooted in the work of famed German engineer Dr. Felix Wankel and development by NSU. In the case of the GS Birotor, its power unit was supplied by Comotor, a joint venture of NSU and Citroën to manufacture Wankel’s engine technology. While NSU’s Ro80 was first to market in 1967, Citroën’s approach was somewhat more conservative, with the Birotor based on the French automaker’s existing Robert Opron-designed GS. This foundation for the Birotor was excellent, as the smallest Citroën to include the company’s renowned hydropneumatic suspension system. In addition to its ultra-low drag, four-door fastback body with aero-efficient Kamm tail, the GS Birotor also sported four-wheel disc brakes, exceptionally comfortable seats, responsive driving dynamics, and peerless ride quality.

The GS Birotor was introduced in October 1973, powered by the same 106 bhp 1,990 cc rotary engine as that of NSU's Ro80. As a technology demonstrator, the GS Birotor cost as much as the larger DS and was less economical to operate, compounded by the 1973 oil crisis. Sales were disappointing and the Birotor was quickly discontinued after 847 were sold. Citroën even attempted to buy back and scrap each example sold, as it did not want to continue supporting the model.

Thankfully, a few of these fascinating small cars have survived in the hands of appreciative collectors. This example was purchased by the Mullin Collection in the Netherlands in 2016. Accompanying this GS Birotor is copies of prior ownership paperwork, a handwritten maintenance logbook spanning 2010–2014 under prior Dutch ownership, and a 2017 Octane magazine article on the model.

*Please note that all of the Lots in this Auction have been in long-term static storage at the Mullin Automotive Museum and may not be currently operational. They will require mechanical attention and in some cases significant restoration prior to any road use.