Volkswagen’s secret W10-powered BMW M5 heads to auction
Words: Kyle Cassidy
An E39 BMW M5 with a Volkswagen engine might sound like an ambitious backyard project. This one, however, was commissioned by Ferdinand Piëch, the engineering enthusiast who ran Volkswagen Group, and reportedly became his personal transport during development.
The unusual machine is heading to Broad Arrow’s Zoute Concours Auction in Belgium on 9 October, with an estimate of €250,000–€350,000. Beneath its understated exterior sits a naturally aspirated 5.0-litre W10, making this rather more interesting than your average engine swap.
According to the auction house, the project explored a potential high-performance saloon engine. BMW’s M5 provided the test platform, with its original V8 removed to accommodate Volkswagen’s experimental ten-cylinder unit.
The W10 produces approximately 353kW and 592Nm, giving it around 59kW more than the standard E39 M5. A six-speed manual gearbox completes a combination that never reached a showroom.
There is a catch for anyone expecting the usual BMW safety net. The conversion deactivated the traction control, stability control and ABS, while the engine runs through a standalone ECU. This remains an experimental machine, with the compromises that description implies.
The engineering story adds considerably to its appeal. Piëch championed Volkswagen’s narrow-angle engine development, and the W10 was part of that experimentation. Broad Arrow places it within the development story that ultimately led to the Bugatti Veyron’s W16.
According to the seller’s account, the work happened outside Volkswagen’s formal research and development department, under Piëch’s direction, with costs reportedly approaching €2 million.
Only three W10 engines were built, according to project engineering leader Sabine Willeke. One remains in Germany, another accompanies the auction lot as a display engine, and the third powers this car.
Finished in Carbon Black Metallic with black leather, the M5 keeps its appearance relatively restrained. Inside, a Stack instrument display replaces the factory cluster, with additional gauges in the centre console. Total mileage cannot be confirmed.
The current owner acquired it roughly a decade ago, subsequently registered it in Slovakia and has continued driving it. Broad Arrow says it was last serviced in 2025, with maintenance drawing on Volkswagen catalogue components.
For a collector, that usability is an intriguing part of the package. Plenty of development cars disappear once their engineering purpose is served. This one survived with its extraordinary engine intact, offering a rare opportunity to buy a working chapter of Volkswagen history disguised as one of BMW’s best-known performance saloons.
