In the footsteps of Moby Dick: Sonderwunsch project with road approval based on a 911 GT2 RS
New silhouette thanks to flatter wheel arches and innovative headlight system
New rear wing featuring S-shaped mounts for even more downforce
Comprehensive lightweight construction measures save a further 31.6 kilograms
Extensive testing carried out, including in the lighting and wind tunnel
“Even greater performance and a Flachbau look, combined with a rear wing à la 911 GT3 R rennsport, please”: these were the specifications set by a Porsche enthusiast who had his like-new 911 GT2 RS transformed into a factory one-off by the Sonderwunsch department. In collaboration with Manthey, a unique, road-legal collector's item was created. Painted in Grand Prix White and equipped with newly shaped wheel arches and a striking, U-shaped contrasting graphic on the hood, the front of the car pays homage to the legendary 935/78 Le Mans racing car nicknamed ‘Moby Dick’.
The Flachbau (otherwise known as slantnose) body style and the Sonderwunsch programme have been closely linked at Porsche for decades. In the 1980s, the sports car manufacturer offered a spectacular modified version of the 911 Turbo (Type 930) with redesigned front wings and pop-up headlights. The design was based on the legendary Porsche 935, which dominated endurance racing for many years. Between 1982 and 1989, 948 examples of this modified version were sold. Even with later conversions taken into account, Flachbau models are still among the rarest variants of the 911 today. Curiosity and intrigue among those on the sports car scene and media world was certainly piqued when it emerged that Porsche had registered the model designations ‘Flachbau’ and ‘Flachbau RS’ with the European Patent Office in May 2025. Now the brand is revealing the secret: the reason for this patent filing was this elaborate transformation of a like-new 911 GT2 RS (Type 991.2) with Weissach Package from 2018.
A multidisciplinary team – comprising experts from the Sonderwunsch department, Style Porsche, and development engineers from Weissach, Porsche Motorsport and Manthey – worked on the project for almost three years. "The conversion to a slantnose model proved to be very challenging, even though we left the drivetrain unchanged in agreement with the customer. Our aim was to reinterpret the iconic look of the 935 without compromising on safety, technology or road approval," explains Alexander Fabig, Vice President Product Offering & Individualisation at Porsche. "Thanks to comprehensive lightweight measures, this one-off car now weighs 31.6 kilograms less than before. That may sound unspectacular at first, but the 911 GT2 RS with Weissach Package is a sports car that is already uncompromisingly optimised in terms of weight reduction."
Responsible for the design of this Sonderwunsch project was Grant Larson, who has since retired. The designer was also the person responsible for the modern interpretation of the 935 that Porsche presented in 2018 as part of its 70th anniversary celebrations. "The new Flachbau RS is a modern, fitting reinterpretation of the iconic 935 Moby Dick design," says Larson. "In addition to the lower front wings, a key feature is the staggered headlight arrangement with very narrow LED units."
The colour scheme also plays on tradition and modern reinterpretation. "We have combined Grand Prix White with sections painted matt black and other areas with exposed carbon fibre," Larson continues. "This creates contrast, and the U-shaped contrasting element at the front picks up on a design feature of the Martini-liveried 935/78 – the famous 'Moby Dick'." The white tone was specially developed for this one-off car. A historic 911 in Grand Prix White from the Porsche AG collection served as a reference.
Purist design: the Flachbau body
The exterior reinterprets the Flachbau shape of the 935. The front wings are now more low-slung and feature slatted air outlets to reduce air pressure. Due to the new contour of the wings, the fuel filler cap and its underlying mechanism and the front bumper also had to be modified. Flaps from Manthey underline the aerodynamic performance of the front end. Instead of the standard round headlights, a new lighting system is used, featuring three very slim LED elements arranged in tiers above one another for high-beam, low beam and daytime running lights. The contrasting elements in black, exposed carbon fibre and Grand Prix White echo the motorsport reference of the 935/78. Aerodiscs on the rear wheels and black brake callipers complete the overall picture.
The front splitter, underbody structure, rear diffuser and carbon-fibre aerodiscs improve aerodynamics and efficiency. The new rear wing with its S-shaped mounts was inspired by the 911 GT3 R rennsport but is about five centimetres higher on this car and can be fixed in three positions. At 340 km/h and in the ‘High Downforce’ setting, the Flachbau RS produces 554 kilograms of downforce on the rear axle.
Spartan perfection: the interior
Inside, the sporty, high-quality feeling in the front of the cabin has been retained, while the rear has been thoroughly stripped back to reduce weight. The Porsche Communication Management (PCM) system, audio components and much of the insulation and cladding were removed. Exposed metal elements in Grand Prix White, carbon trim parts and a deliberately exposed wiring harness emphasise the racing car character. ‘Flachbau RS’ is embroidered on the carbon-fibre bucket seats, behind which a stylised version of the Nordschleife can be seen. A gold-coloured badge with Sonderwunsch lettering and the embroidered words ‘Factory One-Off 2026 | Flachbau RS’ highlights its one-off status. Mandatory items such as the warning triangle and tow eye are housed in a removable emergency box.
Extensive testing: at Weissach and on the Nordschleife
Before producing the new tooling to manufacture the modified components, Porsche digitally validated the design. This process included simplified crash simulations, structural analyses for the loads on the large rear wing and aerodynamic calculations using Computational Fluid Dynamics (CFD). This was followed by testing of the components themselves, including on a Hydropulser test rig and with static load tests. Three test vehicles were built in order to carry out further validation tests in the lighting and wind tunnel as well as on the road. Test drives at Mendig airfield, 50 laps on the Nürburgring-Nordschleife and endurance tests at Weissach combined to simulate about 150,000 kilometres of customer use, most notably for the rear wing. "On the Nordschleife, it becomes immediately clear just how effectively the aerodynamic concept works," says Porsche test driver Lars Kern, who drove the sports car at the Nürburgring. "The Flachbau RS remains extremely stable and precise even at very high speeds. This is precisely the kind of feedback needed to validate such a radically modified body design."
About the Porsche 935
The Porsche 935 was developed on the basis of the 911 Turbo (Type 930) and shaped GT motorsport from 1976 onwards. Its elongated aerodynamic shape earned the 935/78 the nickname ‘Moby Dick’. In 2018, Porsche presented a modern interpretation as a Clubsport racing car.
About Manthey
Manthey specialises in Porsche GT models and has been one of the world's leading Porsche racing teams for 30 years. The company, based in Meuspath near the Nürburgring, employs more than 350 people and is managed by brothers Martin and Nicolas Raeder.
