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1974 Citroën GS Birotor
Country of Origin: France
Design Info: The front-engined, front-wheel drive GS is a compact saloon with an extremely low (for its time) drag coefficient of .318 (comparable to a Lamborghini Diablo or Pagani Huayra). The GS featured Citroën’s self-leveling hydropneumatic suspension, tuned for a small car. The GS Birotor, aside from the engine which it’s named for, differs from the standard GS in having a wider track, wider tires, fender flares, a semi-automatic three-speed transmission, and anti-roll bars to counter the rotary engine’s heavier weight. The Birotor also did away with the standard GS inboard brakes, a necessity from the transverse engine mounting. As compared to flat-4 models of the GS, the Birotor weighs about 700lbs more, or just over 2500lbs total.
Engine Info: While most GS were equipped with air-cooled flat-4 engines from 1.0 to 1.3 liters, the Birotor was powered by a 2.0 liter Wankel 2-rotor developed by Comotor, a partnership between Citroën and NSU to develop and produce such motors. The 2-rotor was almost twice as powerful as the largest flat-4 powering a GS, making 106hp (compared to 66).
Type: A classic, compact family car, the GS was aimed at competition like the Ford Escort, Fiat 128, and especially the Renault 6. However, the Birotor model was significantly more powerful (and more expensive) than the base model, and might have been more in line with sportier models like the Lotus Cortina and BMW 2002.
History: Citroën has always been a company that favored bold ideas. The Traction Avant alone was the first mass-produced front-wheel drive car, the first with four-wheel independent suspension, and the first using unibody construction. Some 20 years later, towards the end of the model’s line, it would also be the first car to use a self-leveling hydropneumatic suspension. That suspension would be perfected on the DS, which would itself be the first mass-produced car using a modern disc brake system. Engineers at the company were also pioneers of aerodynamic design, hydraulic systems, and directional headlights.
Advancement comes with a cost, however. As successful as it would eventually become, the Traction Avant bankrupted the company, causing it to be purchased by its creditor, a tire company called Michelin. It therefore may come as no surprise, then, that the successor car to that model would also be a technologically bold design, and which would also visit severe economic woes on the company.
When, after over 20 years, the final Traction Avants rolled off the line in 1957, its heir apparent was the DS19, a car revealed in 1955 to much admiration and fanfare. However, the DS was significantly more expensive than the Traction Avant, leaving a gap in Citroën’s lineup between the more upscale car and economic 2CV (and later Ami). The company had already begun a project to fill this gap in 1955, called Project C, which developed several bubble car-esque prototypes. None of these, however, were considered suitable for production. In 1963, the company pivoted to Project F.
While this development was ongoing, Citroën had attempted a stopgap solution via proxy. Acquiring a significant stake in Panhard in 1955, the brands’ dealership networks were merged, and eventually Michelin acquired full control of the brand. However, while Panhard models were generally good and did somewhat fill the market niche, they were not seen as Citroëns by the public or the dealers, who felt that the brand image was hurt by the pairing. Michelin needed a mid-range car in the Citroën brand badly.
Unfortunately, Project F would become a disaster. While the new design was not unattractive, it was aerodynamically inefficient. In 1964, the same year that NSU built the first Wankel-engined production car, Citroën formed a joint venture with that company called Comobil to co-develop its own rotary engines. The early iterations of this engine, earmarked for the top-of-the-line Project F model, were dirty, unreliable, and very inefficient. Despite these misgivings, the company geared up for production, purchasing much of the tooling required, and it seemed the mid-size Citroën would finally get on the road. The nail in the coffin for Project F, then, was the Renault 16. With a design similar enough to draw questions of industrial espionage, Renault beat Citroën to market, releasing the 16 in 1965. Worse still, welding techniques used to manufacture the Renault were identical to those necessary to build the Citroën—and Renault had taken the step of patenting the technique, a step that Citroën hadn’t taken, ironically, to avoid copycats. On April 14th, 1967, Project F was dropped, with millions spent on the project lost.
With Panhard ending passenger car production in 1967 (largely planned due to the expected launch of a Project F production car in ‘65) Michelin had become even more desperate for a mid-sized Citroën. Luckily, not everything from Project F was written off. While a new design was necessary, Project G would at least retain many of the mechanical features of the previous concept. Robert Opron, who had been involved in Project F, as well as a redesign of the DS (and who would later design the SM) was pitted in a design competition against Giorgetto Giugaro’s Italdesign to decide the face of Project G. Despite Giugaro’s proposal being quite excellent (later being used for the Alfa Romeo Alfasud), Opron won the day, and the production GS based on his design would be released in 1970.
Opron had also worked on another project for Citroën in this time, called the M35. Produced in small numbers from 1969 to 1971, the M35 would be the first Citroën to employ the fruit of the collaboration with NSU. Now called Comotor, the venture’s first motor for its French parent was a single-rotor 498 cc unit making 49 hp, good for 90mph in the small Ami-based M35. In a strategic move, the cars were sold to buyers who agreed to drive them at least 30,000 km a year, periodically reporting on the vehicle’s performance, in exchange for free technical assistance and a generous buyback offer at the end of the project. Important lessons learned from this project included the need of a larger engine for planned use in the GS, as well as ways to improve the reliability of the engine, which was a serious problem in NSU versions. At the end of the project in 1971, Citroën determined it was ready to put a Wankel engine in the hands of the general public in a GS.
To save money, Citroën tried to avoid significant redesign of the GS to accommodate this newer, larger, more advanced engine. Unfortunately some changes, and therefore expenses, were unavoidable. Despite its generally compact size, the engine was large enough to require transverse mounting, which meant redesign of some brake components. The car would have to be somewhat widened to accommodate the engine and the new axle subframe, and wider tires (with fender flares) were fitted to assist handling with the larger, heavier car. With the weight increase came additional body roll, which was somewhat alleviated with the addition of anti-roll bars. The transmission of the base models was unsuitable, and so a semi-auto box based on an NSU unit was used.
The GS Birotor was finally launched in 1973, with almost twice the power of its siblings. Unfortunately, it also cost over two-thirds more than the base model GS, roughly the same as the DS above it in the model range. The Wankel engine, now more reliable than its NSU kin, was nevertheless just as thirsty, giving the Birotor worse fuel economy than its competitors or even, again, larger cars in higher market segments. Perhaps the public could have forgiven this, in time. Tragically for the Birotor, literal weeks after it was launched King Faisal of Saudi Arabia announced an oil embargo against the nations who supported Israel in the Yom Kippur War, leading to the 1973 Oil Crisis, skyrocketing fuel costs by 300%.
The Birotor never had a chance. Millions were lost in developing a mid-size car through both the C and F projects, not to mention the time spent with no profitable mid-size model throughout that time, and failure with the Birotor and Comotor in general looked to be one more money pit along the way. Citroën had also purchased Maserati in 1968, and by 1975 that company was also hemorrhaging money at an alarming rate. Citroën also lost access to the US market, as laws banning adjustable suspension height made it impossible to sell their cars to American customers. Michelin wanted out, but the French government would not allow a sale of Citroën to foreign owners. Finally, with bankruptcy once again hitting one of the largest French auto manufacturers, a deal was made to merge the ailing company with Peugeot, forming PSA.
The GS itself, like its ancestor the Avant Traction, proved to be successful in the long-term, being sold under PSA until 1986, selling over 2.4 million units when including the facelifted GSA. The Birotor, however, was put to pasture immediately in 1975, after a mere 847 had been sold. The company wanted to distance itself entirely from the Comotor Wankel engines, and issued a recall on the cars, offering large rebates on the new CX model in exchange for returning the Birotors. Returned cars were destroyed, with Citroën taking special care to punch holes in the engines with hydraulic presses, making them unsalvageable. Citroën withdrew type approval, and was given special dispensation by the French government, allowing them to refuse warranties and therefore not keep any Birotor parts in reserve. Even so, some customers refused to return the cars, and some returned cars were not fully scrapped, sitting on lots or in storage, eventually making their way back into private hands. It’s estimated that around a third of the produced cars may still exist.
Why it’s cool/unique/significant: The GS Birotor may seem like an automotive dead-end, one that was such a financial flop it bankrupt and nearly killed its parent company. It was expensive, inefficient, and difficult to live with in some situations (its high-revving engine being particularly unsuited for city driving, amongst other issues). But is that a fair picture of the car?
It’s hard to imagine a worse time to launch any car (save perhaps an econobox) than literal weeks before the 1973 Oil Crisis. Wankel engines were once considered the wave of the future, but were stifled by their fuel economy, with many Wankel projects dying around this time. Mercedes ended their Wankel flirtation around 1970. AMC killed their project in 1974, electing to purchase the then in-development GM Wankel, but GM would also kill their own version later that same year. Ford continued research through the 70s, but filed their last rotary-engine related patent in 1979. NSU was put to rest by Volkswagen in 1977, and the Ro80 with it. Aside from Mazda, only the Soviets pursued the technology into the 80s, and that only resulted in a small number of Wankel-engined Ladas.
Perhaps the poor efficiency of its motor had doomed the Birotor from the start, but Citroën’s version of the engine was already more reliable than the maligned NSU units. With more investment in the technology, perhaps Citroën would have made headway in improving fuel economy as well. Unfortunately, their poor financial decisions in the years before the GS was launched put them at a severe disadvantage in adapting to the hardships they faced. It makes for an interesting what-if, at least, to consider how the Birotor might have fared several years before the crisis, or after, or under a more financially sound company. Perhaps it might have been as influential as the Traction Avant, instead of a footnote in automotive history.
