Porsche’s exclusive Sonderwunsch program, relaunched in 2021 to produce one‑off factory cars for ultra‑wealthy clients, has unveiled its most ambitious project to date: the Flachbau RS. The vehicle is a modern reinterpretation of the 1980s 911 “slant‑nose” Flachbau, built on the chassis of a 2018 911 GT2 RS. A mystery European customer commissioned the build at a cost of several million dollars, and the result is a street‑legal homage that blends classic styling with contemporary performance.
Sonderwunsch program background
The Sonderwunsch service began modestly with a custom‑liveried 911 GT3 for 1985 Le Mans winner Paolo Barilla. It later expanded to more complex builds such as the 993 Speedster and the 997 Classic Club Coupe. Over the last three years, a strike team drawn from Porsche’s own engineering and design groups, along with specialists from Manthey and the Weissach development center, have been tasked with turning the customer’s vision into reality.
Flachbau RS development
Using an eight‑year‑old 911 GT2 RS as a donor, the team stripped the car down to its chassis and powertrain. The customer specifically requested that the powertrain remain untouched; the 3.8‑liter twin‑turbo flat‑six engine continues to deliver 700 horsepower and 553 lb‑ft of torque. All other components were re‑engineered. Long‑time Porsche designer Grant Larson, who also created the modern 935 concept shown at Rennsport Reunion 2018, finalized the design shortly before his retirement.
The front end received a complete overhaul to accommodate the iconic sloping, louvered fenders of the original Flachbau. New bumper, splitter, ultra‑slim headlights and a redesigned fuel filler were required. Manthey contributed additional front‑end aerodynamic elements, including canards and underbody pieces.
Inside, the cabin retains the donor’s red‑and‑black color scheme and carbon‑fiber trim but is largely gutted. The infotainment system and sound equipment have been removed, replaced by a leather‑lined storage cubby where the dash screen once sat. Sound‑deadening material was stripped away, exposing painted metal and even the wiring harness. These measures reduced the vehicle’s weight by roughly 70 pounds compared with a stock GT2 RS.
Technical highlights and validation
The rear features a massive wing mounted on S‑shaped supports. The wing offers three selectable configurations, generating up to 1,221 pounds of downforce at the car’s top speed of 211 mph. Porsche has patented the wing design, preventing direct copies. Because the car must be street‑legal, it underwent the full suite of validation steps required for any production model. This included virtual crash simulations, wind‑tunnel testing, endurance runs, vibration testing of the wing, and a 50‑lap stint on the Nürburgring, where a spy photographer captured one of the test vehicles in August.
The requirement for road legality also meant that the classic 1980s pop‑up headlights could not be used; instead, the new ultra‑slim units meet modern regulations. While trademark filings for the Flachbau name earlier last year and the recent spy photos hint at a possible limited production, Porsche has not announced a broader release. The Flachbau RS remains a bespoke, factory‑produced vehicle, illustrating the extreme creativity and technical capability of the Sonderwunsch division.
For enthusiasts dreaming of a one‑off 911 that marries historic design cues with the raw performance of a GT2 RS, the Flachbau RS stands as a striking example of what is possible when a wealthy client’s imagination meets Porsche’s engineering muscle.
Mitchell Landsberg is the senior reporter for News Raise and focuses on Technology. Mitchell regularly writes about social media platforms and how influencers, industry and general people use them to communicate and make money.
