Porsche Flachbau RS is the ultimate road-legal 935 Moby Dick tribute

Porsche devotees with a particular fondness for slantnose models may recall that the company registered the names ‘Flachbau’ and ‘Flachbau RS’ with the European Patent Office in May 2025. This extraordinary, dreamlike one-off explains why: meet the – yes, really – Flachbau RS.

Starting life as a customer-owned 991.2 911 GT2 RS, itself hardly lacking in menace, it has been remade by Porsche’s internal bespoke division, ‘Sonderwunsch’, into a car resembling ‘Moby Dick’. Not the whale, of course, but Porsche’s famously formidable and rather 'monstrous' racing machine.

Porsche Flachbau RS: a road-legal 935 tribute

“Our aim was to reinterpret the iconic look of the 935 without compromising on safety, technology or road legality,” said Alexander Fabig, Porsche’s VP of individualisation. That means this machine is, remarkably, approved for use on public roads.

In a pleasing coincidence, the one-off’s styling was created by Grant Larson, the same designer behind the 2018 reinterpretation of the 935. Porsche says Larson has now retired, although he described his latest work as follows: “The new Flachbau RS is a modern, fitting reinterpretation of the iconic 935 Moby Dick design.”

Converting a GT2 RS into a slantnose evidently required rather more than a leisurely afternoon’s work. Porsche has fitted newly designed, lower front wings, extra louvres and a fresh front bumper, along with an especially handsome LED lighting arrangement. The lamps are divided into three levels for main beam, dipped beam and daytime running lights.

Manthey aerodynamics and reduced weight

Porsche’s close partner Manthey also contributed to the project. Its involvement brings a new front splitter and rear diffuser, improved aerodynamics over the standard car, and an enormous rear wing. That wing can be set manually in three positions according to the amount of downforce needed – and this is a seriously focused Porsche.

With the wing set to its highest position, it generates 554kg of downforce. The Flachbau RS is also 31.6kg lighter than the standard GT2 RS, which already comes with the weight-saving Weissach Pack, making it an exceptionally light machine.

Unchanged 911 GT2 RS powertrain

Porsche has left the GT2 RS drivetrain alone – and understandably so. Its 3.8-litre twin-turbo flat-six already develops almost 700bhp and 750Nm, delivers 0-100km/h in 2.8 seconds and reaches a top speed of 340km/h. You do not simply… increase the power of a GT2 RS.

The car wears a unique ‘Grand Prix White’ paint finish, contrasted by black details, stripes and aerodisc wheels, while the cabin has been comprehensively stripped back. At the customer’s request, Porsche removed the PCM system, stereo, sound insulation and even the floor coverings.

What remains is painted metal and exposed carbon fibre. Even the wiring loom is on display and, in quintessential Porsche fashion, it was made lighter by deleting “individual wires that were no longer needed”. There is lightweight gearshift gaiter material, and then there is this.

Inside, there is ‘Flachbau RS’ stitching, carbon-fibre bucket seats and a Nürburgring inscription. The final detail is not merely decorative: Porsche completed 50 laps of the ‘Ring in a validation prototype, one of three examples built. After driving there, Porsche test driver Lars Kern said it remained “extremely stable and precise even at very high speeds”. Mission accomplished, then.