In the footsteps of Moby Dick: an extraordinary one-off slantnose model

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 races for 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 in the sports car scene and the media 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 Sonderwunsch department, Style Porsche, and development engineers from Weissach, Porsche Motorsport and Manthey – worked on the project for almost three years. "Converting the car to a slantnose  model proved to be very challenging, even though we left the drive unchanged, in agreement with the customer,” explains Alexander Fabig, Vice President Product Offering & Individualisation at Porsche. “Our aim was to reinterpret the iconic look of the 935 without compromising on safety, technology or road legality. Thanks to thorough lightweight measures, this one-off car now weighs 31,6 kg less than before. That may sound unspectacular at first, but the 911 GT2 RS with Weissach Package is a sports model 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. His involvement was a special stroke of luck; after all, he had also designed the modern interpretation of the 935 that Porsche unveiled in 2018 to mark the 70th anniversary of the legendary racing car. "The new Flachbau RS is a modern, fitting reinterpretation of the iconic 935 Moby Dick design," says Larson. "In addition to the flatter front wings, a key feature is the staggered headlight arrangement with very narrow LED units."

The colour scheme also deliberately 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 contrast element at the front echoes a design feature of the Martini-liveried 935/78 – the famous 'Moby Dick'. The special white tone was specially developed for this one-off car. A historic 911 in Grand Prix White from the Porsche AG collection served as the reference, which the experts used to precisely match the colour shade.

Purist design: the Flachbau body

The exterior reinterprets the legendary Flachbau shape of the 935. The front wings are now more low-slung and feature slatted air outlets. These louvres vent the wheel arches and reduce the air pressure within. Due to the new contour of the wings, the  fuel filler flap and the underlying mechanism also had to be modified. The front bumper has also been completely redesigned. Subtle black flaps from Manthey underline the aerodynamic performance at the front end.

A cleverly designed lighting system is used in the place of the standard round headlights. The three LED elements for high-beam, low beam and daytime running lights are arranged in tiers above one another. The individual light units are very slim: the low beam and high beam each measure just under four centimetres in height, and the daytime running lights are even more slender at less than two cm.

The factory one-off car is painted in Grand Prix White, a traditional Porsche colour introduced for the 911 in 1974. Contrasting elements in black providing striking accents against the exterior paintwork.  Particularly eye-catching are the stripes on the bonnet and roof, which are inverted compared to the standard GT2 RS model. The centre stripe and the U-shaped contrasting element are presented in black exposed carbon fibre, surrounded by Grand Prix White. The aerodiscs fitted to the rear wheels are also finished in Grand Prix White, while the brake callipers round off the sporty look painted in deep black.

The front splitter, in combination with the underbody structure of the Manthey Kit including the rear diffuser, enhances aerodynamics and ensures uncompromising performance. The carbon-fibre aerodiscs on the rear wheels reduce drag. The new rear wing with S-shaped mounts was inspired by that of the 911 GT3 R rennsport (Type 992) but is approximately five centimetres higher on this car.

It can be manually fixed in three different positions to provide different levels of downforce depending on the track requirements. In the ‘High Downforce’ and ‘Low Downforce’ settings, the downforce on the rear axle is two and three per cent higher, respectively, compared to a 911 GT2 RS with Manthey Kit with the wing in the corresponding positions. At a top speed of 340 km/h in the ‘High Downforce’ setting, the Flachbau RS produces exactly 554 kg of downforce on the rear axle. The wing adjustment and the corresponding position markings are protected by patent.

Spartan perfection: the interior

Before the conversion, red Alcantara, black leather and exposed carbon fibre characterised the interior. In the front area of the cabin, as far back as the seats, the same look and feel was retained. Whereas the area behind the seats, much like a racing car, has been thoroughly stripped out.

Numerous comfort elements fell victim to the radical lightweight approach. The Porsche Communication Management (PCM) system was removed and replaced by a leather-trimmed storage compartment. All components of the audio system were also removed. Sound-deadening materials and floor coverings in the interior and luggage compartment were also largely removed in the pursuit of weight reduction.

Instead, many parts are now presented in spartan metal painted in Grand Prix White, typical of racing cars. Selected surfaces, such as the extension of the armrest, are clad with carbon trim. The newly laid wiring harness has deliberately been left exposed and is covered only by protective sheathing. To reduce weight even further, individual wires that were no longer needed have been removed.

‘Flachbau RS’ lettering is embroidered on the headrests of the carbon-fibre bucket seats, behind which the stylised outline of the Nordschleife can be seen. On the passenger side, the dashboard is adorned with a gold-coloured badge with ‘Sonderwunsch’ lettering and the inscription ‘Factory One-Off 2026 | Flachbau RS’ engraved on a plate.

The conventional mounting points in the body for components such as the warning triangle and towing eye have been removed. These elements, which are mandatory for road cars, are now housed in a practical ‘emergency box’. If the Flachbau RS is to be driven on track, the box can easily be removed from the car in order to minimise the overall weight.

Extensive testing: at Weissach and on the Nordschleife

After the fundamental details of the design were defined, extensive digital validation was carried out. This included simplified crash simulations and tests to validate the airbag deployment. In addition, detailed structural analysis was carried out, particularly with regard to the loads on the large rear wing. Finally, aerodynamic calculations were carried out using Computational Fluid Dynamics (CFD) in order to further optimise the overall design. It was only after these virtual tests had been successfully completed that the go-ahead was given for the production of new tooling to manufacture the modified components.

This was followed by technical validation of the individual components. The new rear wing was subjected to extreme vibrations on a hydropulse test rig, similar to the vibrations encountered – albeit to a lesser extent – during road use. In addition, the experts also tested its static load-bearing capacity using sandbags.

A total of three test vehicles were built in order to carry out further validation tests in facilities such as lighting and wind tunnels, as well as during real-world road tests. Numerous test drives at the Mendig airfield, 50 laps on the Nürburgring-Nordschleife alone and endurance tests at the Weissach site combined to simulate a load on the rear wing equivalent to about 150,000 kilometres of customer use.

"On the Nordschleife, it becomes immediately clear how cleanly aerodynamic concepts work," says Porsche test driver Lars Kern, who drove the sports car on the famous track. "The Flachbau RS remains extremely stable and precise even at very high speeds. This is exactly the kind of feedback needed in order to validate such a radically altered body design."

Even experienced prototype hunters and motorsport fans were impressed: when a camouflaged slantnose test car completed laps at the Nürburgring, videos of the event racked up more than 100,000 views on social media within a few hours.

About the Porsche 935

Developed based on the Type 930 911 Turbo, the 935 caused a sensation on race tracks from 1976 onwards. Porsche won the World Championship for Makes four times in a row with it. It dominated the 12 Hours of Sebring several times, as well as the 24 Hours of Daytona. At Le Mans, it achieved both class wins and overall victories. Few other production-based racing cars have achieved so much success. It was primarily the elongated shape of the 935/78 that earned the now legendary racing car the nickname ‘Moby Dick’. 

As part of the Rennsport Reunion in 2018, Porsche presented a modern interpretation of the 935. To mark the ‘70 years of Porsche sports cars’ anniversary, a 700 PS clubsport racing car was produced in a limited run of just 77 units.

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 the brothers Martin and Nicolas Raeder.

Manthey boasts an impressive track record: its greatest motorsport achievements include seven overall victories at the Nürburgring 24 Hours, six class victories at the 24 Hours of Le Mans, eight titles in the FIA World Endurance Championship and victory in the teams' and drivers' championships in DTM in 2023 and 2025.