The M5 That Never Was: VW’s Wild W-10 Prototype

The story of the Volkswagen W-10-powered BMW M5 sounds like something out of an automotive fever dream—a bizarre chapter of Bavarian and Wolfsburg engineering that almost feels too wild to be true. But here it is, a real-deal prototype blending BMW's iconic E39 M5 with a VW-built, one-off W-10 engine.

Volkswagen apparently made at least three of these W-10 engines, but the decision to shove one into a third-gen M5 remains a bit of a mystery.

The theory goes that VW needed a high-performance sedan before the Porsche Panamera was even a concept, and the M5 was a perfect mule for testing. Dyno runs reveal it puts down 480 hp to the wheels, which means it likely cranks out around 530 hp at the crank—well above the stock M5’s 394 hp from its S62 V8 and even topping the 500 hp of the later S85 V10 in the E60 M5.

The engine itself is a fascinating piece of engineering, supposedly created by fusing two 2.5-liter VR5s. But instead of sticking with the iron block typical of VR engines, VW opted for a cast aluminum one. The result was a strange and experimental powerplant—unique enough that former VW boss Ferdinand Piëch reportedly used the prototype as his personal ride. You have to wonder if he saw a future for the W-10 beyond just a quirky test mule.

Unfortunately, despite the rumored €2 million investment, the W-10 never made it to a production car. The Bentley connection makes sense given the W-12’s success, but the W-10 was likely too experimental and costly to mass-produce. In true VW Group fashion, the project was ultimately shelved. The W-8, W-12, and W-16 had their time in the spotlight, but the W-10 became a footnote—an enigma driven by Piëch himself.

Drivetribe’s chance to drive the car must have been a surreal experience. Rear-wheel drive, six-speed manual, no stability control or ABS—this M5 is raw, unforgiving, and sounds like a genuine beast. It’s an outlaw among M5s, with a strange soul that bridges the gap between BMW and VW engineering.

While the W-10 remains a prototype oddity, it’s a reminder of VW's wild ambitions during the Piëch era, when engine configurations were as varied as the brands in the Volkswagen Group portfolio. With W engines now a thing of the past, the W-10 M5 feels like a relic from an alternate timeline—one where the wildest ideas didn’t stay on the drawing board.