PORSCHE'S FLACHBAU RS SHEDS 31.6 KILOS FOR DOWNFORCE

PORSCHE'S FLACHBAU RS SHEDS 31.6 KILOS FOR DOWNFORCE

Porsche's Sonderwunsch division removed 31.6 kilograms from the Flachbau RS without opening the engine bay. The one off 911 GT2 RS commission, revealed in August 2026, carries a three position adjustable wing rated for 554 kilograms of downforce at 340 kilometers per hour. Every gram cut and every kilogram of downforce added points at one brief: make a road legal tribute to the 935/78 Moby Dick racer behave like the car it copies, not just resemble it.

554 Kilograms Arrives at 211 Miles Per Hour

The wing, set to its most aggressive of three positions, works with a Manthey developed diffuser, front splitter, carbon fiber aerodiscs and an underbody tray to produce 554 kilograms, or 1,221 pounds, of downforce at 340 km/h. That is the top speed figure Porsche quotes for the finished car, so the aero package is rated for the car's own stated ceiling, not a wind tunnel number nobody will reach on public roads.

Three wing positions matter more than the peak figure alone. A fixed angle would either drag at low speed or fall short at the top end. Sonderwunsch built in adjustment so the owner can trade drag for downforce depending on the road, borrowing the logic Porsche already uses on the factory GT3 RS wing and applying it to a body the GT3 RS never wore.

Manthey Racing Engineered the Diffuser, Weissach Did Not

Manthey Racing, the Nurburgring based outfit that has built Porsche's GT customer racing aero kits for two decades, developed the diffuser, splitter, aerodiscs and underbody tray on this commission instead of Porsche's in house design studio. That handoff is specific, and it explains why the Flachbau RS reads like a customer racing package wearing a road registration instead of a design department showpiece with a big wing bolted on.

The aerodiscs, vaned covers fitted over each wheel, are a Manthey signature pulled from their GT3 R race program. Porsche's own GT3 Weissach package trims roughly 48 pounds through carbon fiber panels and forged magnesium wheels using Weissach's in house process, a different lightweighting route than the external kit built for the Flachbau RS.

31.6 Kilograms Came Off an Already Light Car

The build starts from a 911 GT2 RS fitted with the Weissach package, Porsche's lightest specification for the model, already built around magnesium wheels and a stripped rear cabin. Cutting a further 31.6 kilograms from that base took additional lightweight body panels and a race style interior, not one dramatic swap.

The Flachbau RS build brought designer Grant Larson out of retirement to draw the slantnose nose and reshaped wheel arches years before these aero and weight figures existed, which is why the bodywork reads as a period correct 935 homage instead of a modern widebody kit bolted onto a GT2 RS shell after the fact.

554 KG Beats the Factory GT3 RS by 145

Porsche's own 911 GT3 RS produces 409 kilograms of downforce in its stock Weissach configuration, the number the brand showed off at its most recent Sportscar Together Day event. The Flachbau RS clears that by 145 kilograms, running a wing plus four external aero components against the GT3 RS's wing and diffuser alone.

That gap is what separates this build from a styling exercise. A single customer Sonderwunsch commission now out produces Porsche's own homologated RS flagship on downforce, engineered with an outside partner instead of the department that develops the production cars. It lands the same month enthusiasts wrapped a stock GT3 RS in chocolate brown paint purely as a style statement, the kind of fashion crossover that usually follows a car once it stops being a lap time exercise. The Flachbau RS is headed the opposite direction, treating the body as a performance instrument before anyone gets to treat it as a canvas.

One Customer, No Repeat Planned

Porsche built exactly one Flachbau RS, for a single customer, and has said the car is not for sale. The 554 kilogram figure will not appear on a build sheet again unless Sonderwunsch chooses to reuse the aero package for a future commission, and the department has not said that is coming.

Sonderwunsch commissions have historically stayed inside Porsche's own walls, drawn by the in house design team and built by Zuffenhausen technicians without an outside partner's name on the parts list. Bringing in Manthey for the diffuser, splitter, aerodiscs and underbody tray breaks that pattern, and it happened on a car built to resemble a 1978 Le Mans racer rather than a current customer GT car.

What the numbers confirm is that Sonderwunsch is now willing to bring in outside performance engineering instead of keeping every commission a styling exercise handled entirely in house. If that continues, the next one off Weissach ships with the design story and the race package specs written by two different teams aimed at one finished car, and the 554 kilogram figure on this build stops being an outlier and starts being a baseline.