Porsche has revealed one of its most extraordinary modern one-off creations: the Porsche Flachbau RS, a radically transformed 911 GT2 RS developed through the brand’s exclusive Sonderwunsch programme in collaboration with Manthey.

Based on a virtually new 2018 Porsche 911 GT2 RS Type 991.2 with the Weissach Package, the Flachbau RS combines the brutal performance of Porsche’s most extreme 991-generation 911 with a dramatically redesigned body inspired by the legendary Porsche 935/78 Le Mans racing car, famously known as “Moby Dick.”

The result is a road-legal collector’s car that looks unlike any standard 911 GT2 RS.

The project took almost three years to complete and involved specialists from Porsche Sonderwunsch, Style Porsche, Porsche Motorsport, Weissach development and Manthey. Despite the extensive transformation, the original powertrain was retained.

More importantly, Porsche says the finished car is 31.6 kilograms lighter than the already highly weight-optimised 911 GT2 RS Weissach.

The Flachbau Returns to Porsche

The name Flachbau has a special place in Porsche history.

Also known as “slantnose”, the Flachbau design first became famous in the 1980s when Porsche offered a heavily modified version of the 911 Turbo Type 930. Instead of the traditional 911 front end, the car featured dramatically reshaped front wings and pop-up headlights.

The design was heavily influenced by Porsche’s successful 935 racing cars.

Between 1982 and 1989, Porsche sold 948 examples of the modified 911 Turbo. Even when later conversions are considered, genuine Flachbau models remain among the rarest versions of the classic 911.

That history makes the new Flachbau RS particularly significant.

Porsche had already fuelled speculation in May 2025 when it registered the names “Flachbau” and “Flachbau RS” with the European Patent Office. The reason for those registrations has now become clear.

They were connected to this remarkable factory one-off.

A Modern Interpretation of the Porsche 935 Moby Dick

The design responsibility for the Flachbau RS was given to Grant Larson, the Porsche designer who has since retired.

That choice was particularly appropriate because Larson was also responsible for the modern Porsche 935 unveiled in 2018 to celebrate the 70th anniversary of the legendary racing car.

For the Flachbau RS, the goal was not simply to recreate the 935/78.

Instead, Porsche wanted to reinterpret its most recognizable design elements for a modern road-going 911.

The result is an aggressive front end with significantly lower front wings, new aerodynamic openings and an unusual headlight arrangement that immediately separates the Flachbau RS from the standard GT2 RS.

The inspiration from the famous “Moby Dick” is especially visible in the U-shaped graphic on the bonnet.

Grand Prix White Meets Exposed Carbon Fibre

The Flachbau RS is finished in Grand Prix White, one of Porsche’s most iconic colours.

The shade was specially developed for this particular car, with Porsche using a historic Grand Prix White 911 from its own collection as the colour reference.

The white bodywork is contrasted with matt black elements and exposed carbon fibre.

One of the most distinctive features is the bonnet and roof graphics. Unlike the standard GT2 RS design, the stripes have been inverted, creating a strong visual contrast.

A central stripe and the U-shaped element are made from black exposed carbon fibre and surrounded by Grand Prix White.

The rear-wheel aerodiscs are also painted white, while the brake calipers are finished in deep black.

It is a colour combination that deliberately mixes Porsche’s racing heritage with the technical appearance of a modern GT car.

The Most Important Change Is at the Front

The defining feature of the Porsche Flachbau RS is, of course, its new front end.

The front wings are considerably lower and feature slatted air outlets designed to vent the wheel arches and reduce air pressure.

Because the new bodywork changes the shape of the front wings, Porsche also had to modify the fuel filler flap and its underlying mechanism.

The front bumper was completely redesigned as well.

Small black aerodynamic flaps developed with Manthey add another layer of visual aggression while contributing to the car’s aerodynamic performance.

But perhaps the most fascinating part of the redesign is the lighting system.

Instead of the conventional round headlights of the 911 GT2 RS, the Flachbau RS uses three slim LED elements arranged vertically.

The high beam, low beam and daytime running light are stacked above one another.

The low- and high-beam units are each less than four centimetres tall, while the daytime running light is less than two centimetres high.

The result is a distinctive face that combines the low-slung appearance of the original Flachbau with modern LED technology.

A New Rear Wing Inspired by the 911 GT3 R Rennsport

The front of the car may be inspired by the 935, but the rear wing comes from another part of Porsche’s motorsport world.

The massive rear wing features S-shaped supports inspired by the Porsche 911 GT3 R Rennsport Type 992.

On the Flachbau RS, however, the wing sits approximately five centimetres higher.

The wing can be manually adjusted into three different positions, allowing the driver to alter the aerodynamic balance depending on the intended use.

According to Porsche, the aerodynamic performance is improved compared with a 911 GT2 RS equipped with the Manthey Kit and using the corresponding wing settings.

At 340 km/h in the High Downforce setting, the Flachbau RS generates exactly 554 kg of downforce on the rear axle.

The wing adjustment mechanism and position markings are also protected by patent.

Manthey Aerodynamics Take the GT2 RS Even Further

The Flachbau RS is more than a visual exercise.

Manthey’s aerodynamic expertise plays a major role in the car’s transformation.

A redesigned front splitter works together with the underbody components and rear diffuser from the Manthey Kit to improve aerodynamic performance.

At the rear, carbon-fibre aerodiscs reduce aerodynamic drag while maintaining the aggressive motorsport-inspired appearance.

The combination of the new bodywork, underbody aerodynamics and large rear wing gives the Flachbau RS a substantially different aerodynamic character from a standard 911 GT2 RS.

And Porsche did not simply install the parts and send the car to its owner.

The entire package went through an extensive engineering and validation programme.

Nearly 32 Kilograms Lighter Than the GT2 RS Weissach

Weight reduction was another major objective.

That is especially impressive because the starting point was already a 911 GT2 RS with the Weissach Package, a car designed from the beginning to minimise weight.

Nevertheless, Porsche managed to remove 31.6 kg from the vehicle.

A significant part of the weight reduction came from the interior.

The Porsche Communication Management system was removed and replaced by a leather-trimmed storage compartment.

The audio system was deleted, while sound insulation, carpeting and other interior materials were substantially reduced or removed.

The rear section of the cabin has been transformed into something much closer to a racing car.

Instead of a conventional finished interior, various components are exposed and painted in Grand Prix White.

Carbon-fibre trim is used selectively, while parts of the newly arranged wiring harness remain visible beneath protective sheathing.

Even unnecessary wiring was removed in the pursuit of weight savings.

A Racing Interior for a Road-Legal Car

The front section of the cabin retains much of the original red Alcantara, black leather and exposed-carbon look of the GT2 RS.

Behind the seats, however, the philosophy changes dramatically.

The interior becomes deliberately spartan.

The carbon-fibre bucket seats feature “Flachbau RS” embroidery, with a stylised outline of the Nürburgring Nordschleife positioned behind the lettering.

On the passenger side of the dashboard sits a gold-coloured Sonderwunsch badge.

A dedicated plaque carries the inscription:

“Factory One-Off 2026 | Flachbau RS”

Even mandatory road-car equipment has been reconsidered.

The conventional mounting points for items such as the warning triangle and towing eye were removed. Instead, these components are stored in a removable emergency box.

When the car is used on a circuit, the box can be taken out to save additional weight.

Porsche Had to Prove the Flachbau RS Was Safe

Creating a one-off body for a high-performance road car is considerably more complicated than simply designing new panels.

Porsche carried out extensive digital validation before approving production.

The engineering process included simplified crash simulations, airbag deployment validation and detailed structural analysis.

One of the most important areas of investigation was the enormous rear wing and the forces it generates at high speed.

Porsche also used Computational Fluid Dynamics (CFD) to analyse and optimise the car’s aerodynamic characteristics.

Only after the virtual validation process had been completed did Porsche approve the production of new tooling for the redesigned components.

Three Test Cars and 50 Nürburgring Laps

The validation process continued with physical testing.

The new rear wing was subjected to extreme vibrations on a hydropulse test rig designed to simulate the stresses experienced during road use.

Its static load capacity was also tested using sandbags.

Porsche ultimately built three test vehicles for the development programme.

These cars underwent lighting and wind-tunnel testing, real-world road testing and extensive durability testing.

Testing included numerous runs at Mendig airfield, endurance work at Porsche’s Weissach facility and 50 laps of the Nürburgring-Nordschleife.

In total, Porsche says the testing simulated a load on the rear wing equivalent to approximately 150,000 kilometres of customer use.

That level of testing illustrates how seriously Porsche approached the transformation.

The Flachbau RS may be a single road-legal collector’s car, but Porsche wanted it to meet the company’s standards for safety, durability and performance.

Tested by Lars Kern at the Nürburgring

Porsche test driver Lars Kern was among those responsible for evaluating the finished car on the Nürburgring.

The Nordschleife is particularly useful for assessing aerodynamic stability because of its combination of high-speed sections, elevation changes and complex corners.

According to Kern, the Flachbau RS remained stable and precise even at extremely high speeds.

That is an important achievement considering how extensively the original GT2 RS bodywork was modified.

The testing was not simply about proving that the car could survive.

It was about making sure that the new aerodynamic concept behaved predictably at the limit.

The Prototype That Became an Internet Sensation

Before Porsche officially revealed the Flachbau RS, the project had already attracted attention.

A camouflaged slantnose prototype was spotted testing at the Nürburgring, where videos quickly appeared on social media.

Those videos reportedly generated more than 100,000 views within just a few hours.

For Porsche enthusiasts, the unusual silhouette was immediately intriguing.

A modern 911 GT2 RS with a dramatically reshaped front end was clearly something different, and the appearance of the prototype only intensified speculation surrounding the Flachbau and Flachbau RS trademarks.

Now the mystery has been solved.

Porsche Flachbau RS Specifications at a Glance

• Base car: Porsche 911 GT2 RS Type 991.2
• Model year of base car: 2018
• Package: Weissach Package
• Programme: Porsche Sonderwunsch
• Development partner: Manthey
• Design: Grant Larson
• Exterior colour: Grand Prix White
• Inspiration: Porsche 935/78 “Moby Dick”
• Rear wing inspiration: Porsche 911 GT3 R Rennsport
• Weight reduction: 31.6 kg
• Top speed: 340 km/h
• Rear-axle downforce at 340 km/h: 554 kg in High Downforce setting
• Rear wing positions: Three
• Test vehicles: Three
• Nürburgring testing: 50 laps
• Simulated rear-wing durability: Approximately 150,000 km
• Production: Factory one-off
• Road legal: Yes

A 911 GT2 RS Unlike Any Other

The Porsche Flachbau RS is not simply another special-edition 911.

It is a demonstration of what happens when Porsche’s Sonderwunsch programme is given almost unrestricted creative and engineering freedom.

The starting point was already one of the most extreme road-going 911s ever produced: the 991.2-generation GT2 RS with the Weissach Package.

From there, Porsche transformed the car’s identity.

The traditional 911 silhouette was replaced by a modern interpretation of the Flachbau design. The front end pays tribute to the 935/78 Moby Dick, the rear wing draws inspiration from the 911 GT3 R Rennsport, and Manthey’s aerodynamic expertise adds genuine functional performance.

Most importantly, the project retains the spirit of Porsche’s motorsport heritage without turning the car into a mere historical replica.

It is a modern Flachbau for the GT2 RS generation.

And perhaps that is what makes the Porsche Flachbau RS so fascinating: it connects three different eras of Porsche performance in a single machine—the legendary 935 of the late 1970s, the iconic Flachbau 911 Turbo of the 1980s, and the brutally fast 991.2 GT2 RS of the modern era.

For collectors, it represents something even more valuable.

There is only one.

Source: Porsche