A rare W10 BMW M5 prototype built at Ferdinand Piëch’s request in 1999 is heading to auction, offering a unique look at an experimental engine program that ultimately disappeared without entering production. The one-off E39 M5 features a 5.0-liter naturally aspirated W10 producing 473 horsepower and 437 pound-feet of torque.
A 5.0-Liter W10 Engine in an E39 BMW M5
In 1999, Piëch instructed his engineers to develop a W10 engine for a high-performance sedan. Rather than creating a dedicated test vehicle, the experimental engine was installed in an E39 BMW M5 that had been stripped of its original 4.9-liter naturally aspirated S62 V8.
The all-aluminum, naturally aspirated 5.0-liter W10 produced 473 hp and 437 lb-ft of torque. That represented an increase of 79 hp and 68 lb-ft over BMW’s factory V8, while the car retained its six-speed manual transmission.
The W10 was created by fusing two VR5 engines together, with the cylinders sharing a common crankshaft. The configuration was designed to deliver power with exceptional smoothness.
VW Group Spent Nearly €2 Million on the Experiment
The experimental M5 was fitted with a standalone ECU, while its traction control, stability control and anti-lock brakes were deactivated. The setup was said to give the car a more immediate character than a factory E39 M5, combining smooth power delivery with quicker engine response.
According to the current owner, who spoke with Broad Arrow Auctions, the unofficial experiment cost VW Group nearly €2 million. Because the project was never an official program, development was conducted outside the company’s R&D department under Piëch’s specific instructions.
Sabine Willeke, who led the engineering team behind the project, told the auction house that only three W10 engines were ever built. One remains in Germany, presumably at Volkswagen, another is being offered alongside the experimental M5 as a display example, and the third is the engine installed in the car.
No other W10 engine was installed in a road-going vehicle, and VW never returned to the W10 concept after the program ended. That makes the W10-powered E39 M5 particularly unusual.
Ferdinand Piëch Personally Drove the Prototype
From the outside, there is little indication that the M5 houses an experimental engine. The car is finished in Carbon Black Metallic with a Black leather interior, while chassis number WBSDE91040GJ16436 gives it the appearance of a standard E39 M5.
Inside, however, the car features an aftermarket Stack dashboard without an odometer reading, making its mileage impossible to determine. Additional gauges were also installed in the center console.
Despite being an informal experimental prototype, the W10 M5 was developed into a fully drivable vehicle with careful attention to its engineering details. The custom intake ducting, ignition system and coolant expansion tank were neatly integrated into the car.
The prototype was also driven by Ferdinand Piëch himself on temporary plates during its secret development and testing.
One-of-a-Kind M5 Heads to Auction
The current owner acquired the unusual M5 about a decade ago through connections in the engineering world and later registered it for road use in Slovakia. The owner continues to drive the car rather than keeping it in storage, although it does not have a certificate of conformity.
Broad Arrow Auctions will handle the vehicle’s sale on October 9. The auction house estimates that the one-of-a-kind W10 BMW M5 could sell for between €250,000 and €350,000, or approximately $285,000 to $400,000.
