Porsche’s one-off GT2 RS Flachbau RS brings the 935 Moby Dick’s face back to a street legal 911

Porsche has brought the Flachbau concept back to the 911 through one of the most involved Sonderwunsch commissions the programme has taken on in years. The starting point was a 2018 911 GT2 RS Type 991.2 fitted with the Weissach Package, transformed into a one-off, road legal special after nearly three years of development involving Style Porsche, engineers from Weissach, Porsche Motorsport and Manthey. The owner’s brief was straightforward on paper and enormous in practice: even higher performance, a Flachbau front end, and a rear wing inspired by the 911 GT3 R rennsport, all while leaving the powertrain untouched.

Reinterpreting the 935 and the 935/78 Moby Dick

The result reinterprets the Porsche 935, and specifically the 935/78 Moby Dick, through lowered front fenders, ultra slim LED light clusters stacked across three levels, dedicated aero elements and a Grand Prix White livery finished with exposed carbon and matte black. The lightweighting effort stripped out roughly 32 kg, while the new adjustable rear wing can generate even more downforce than a GT2 RS already fitted with the Manthey Kit. Before road homologation, Porsche ran three development cars through crash simulations, CFD analysis, wind tunnel testing, 50 laps of the Nürburgring Nordschleife, and durability testing equivalent to roughly 150,000 km of real world use.

Flachbau: bringing the 911 back toward the 935

The Flachbau name, also known as Slant Nose, has been part of Porsche culture for decades. Back in the 1980s, Porsche’s in-house customisation programme offered a 911 Turbo Type 930 with heavily reworked front fenders and pop-up headlights, directly referencing the competition focused 935. Between 1982 and 1989, Porsche built 948 examples of that special version, a rarity that still makes original Flachbau cars among the most sought after 911 variants today.

Porsche Sonderwunsch one-off designed by Grant Larson

Design duties fell to Grant Larson, who previously led the modern reinterpretation of the Porsche 935 unveiled at Rennsport Reunion VI in 2018. His work here takes the proportions of the historic 935 and maps them onto the GT2 RS 991.2’s structure. The nose visually drops through new fenders and loses the 911’s traditional round headlights entirely, a single change that immediately shifts how the whole car reads.

New fenders manage wheel arch pressure, not just looks

The front fenders sit lower and incorporate louvred vents up top, designed to bleed air out of the wheel arches and cut down on pressure buildup at high speed. Reshaping the fenders also meant redesigning the fuel filler door and its mechanism, a small detail that shows just how deep the Flachbau transformation runs into the car’s actual bodywork rather than sitting on the surface. The front bumper is entirely new too, incorporating small canards developed by Manthey.

Three stacked LED elements replace the 911’s round headlights

The most visible change is the lighting. In place of the traditional circular headlights, three separate LED elements handle high beam, low beam and daytime running lights, stacked vertically across different levels. The high and low beam elements each measure under 1.5 inches in height, while the daytime running light drops below 0.78 inches. That packaging is what allows the fender profile to sit so low while still meeting road legal lighting requirements.

Grand Prix White and carbon echo the 935/78 Moby Dick

The chosen colour is Grand Prix White, a shade Porsche originally introduced on the 911 in 1974. For this car, the paint was recreated by referencing a historic 911 held in the Porsche AG collection, matching the original tone precisely. White pairs with matte black and exposed carbon fibre, and a distinctive graphic running across the bonnet and roof, a central stripe with a U shaped element, directly references the Martini liveried 935/78 known as Moby Dick.

Manthey aerodynamics reshape the GT2 RS underneath

Front end work pairs with the Manthey Kit’s underbody structure and a dedicated rear diffuser. The rear wheels get carbon fibre aero discs finished in Grand Prix White, developed specifically to cut aerodynamic drag. The centrepiece, though, is the new rear wing, mounted on S shaped supports and inspired by the solution used on the 992 generation 911 GT3 R rennsport.

A rear wing adjustable across three positions

On the Flachbau RS, the wing sits almost two inches taller than its reference point and can be manually adjusted across three positions, letting owners tune aerodynamic balance to suit different circuits. In the High Downforce and Low Downforce settings, rear axle load increases by 2 and 3 percent respectively compared with a 911 GT2 RS running the Manthey Kit in equivalent positions. The wing adjustment mechanism and its position markings are patent protected. In line with the owner’s request, Porsche left the powertrain completely unchanged.

A cabin stripped toward the back, road focused up front

Up front, the cabin keeps red Alcantara, black leather and exposed carbon fibre, while the area behind the seats takes on a look much closer to a race car. The Porsche Communication Management system has been removed entirely and replaced with a leather trimmed storage compartment. The audio system is gone too, along with much of the sound deadening material and several floor and boot trim panels.

Plenty of surfaces are left in bare metal finished in Grand Prix White, with wiring deliberately left visible under a simple protective sleeve, and any wiring no longer needed removed entirely rather than just disconnected.

Carbon shell seats reference the Nordschleife

The carbon fibre shell seats carry embroidered “Flachbau RS” lettering, with a stylised outline of the Nürburgring Nordschleife stitched behind them. On the passenger side of the dashboard sits a gold plaque bearing the Sonderwunsch signature and the engraving “Werksunikat 2026 – Flachbau RS”, formally marking the car as a genuine factory one-off. Even the warning triangle and tow hook have been relocated from their usual mounting points into a removable box, making them easy to pull out entirely for track use.

Three prototypes and 50 Nordschleife laps to homologate the body

A transformation this extensive demanded full validation. Porsche ran crash simulations, airbag deployment checks, structural analysis of the loads generated by the wing, and CFD aerodynamic simulations before signing off production of the new tooling needed for the modified components. Three test cars were then built and put through wind tunnel testing, dedicated lighting tests and on road evaluation. The dynamic testing phase included runs at Mendig airfield, 50 laps of the Nürburgring Nordschleife, and durability testing at Weissach.

Flachbau RS ties together three generations of the 935

There’s a fairly precise historical thread running behind this one-off. The original Porsche 935 emerged in 1976 from the 911 Turbo Type 930, becoming one of the most successful competition cars derived from the 911 during its era. The 935/78 earned its Moby Dick nickname largely from its dramatically elongated bodywork. In 2018, Porsche revisited the concept with a modern, track only 935 producing 700 PS, built in just 77 examples. The 2026 Flachbau RS adds a third chapter to that story, applying the 935’s design language to a road going GT2 RS through a fully individual factory project.

Porsche 911 GT2 RS Flachbau RS: key specifications