Long before Dieselgate, draconian emissions regulations, and aggressive cost-cutting, Volkswagen had an era of impressive engineering. During the ruthless leadership of Ferdinand Piëch, there were no limits to what the engineers could cram under the hood. The VW Group experimented with everything, including W-8 and W-12 sedans as well as V-10 and V-12 diesel SUVs. Heck, it even made an R8 with a twelve-cylinder TDI.
Under VW’s umbrella, Bugatti gave us the W-16 Veyron, but only after teasing an even wilder W-18 concept. Yet, the eighteen-cylinder beast wasn’t the only radical engine left on the cutting room floor. Enter the forgotten W-10. VW modified an M5 with a ten-cylinder engine before BMW rolled out the E60/E61 with its naturally aspirated 5.0-liter V-10. For years, the W-10-powered M5 was nothing more than a myth until the prototype surfaced for sale in 2023. Fast-forward to 2025, and Drivetribe finally got the chance to check out this elusive Bavarian luxury sports sedan with a heart transplant from a donor in Wolfsburg.
Volkswagen built at least three W-10 engines, one of which found its way into a third-generation M5 (E39). But why? At the time, VW lacked a comparable high-performance sedan in its lineup. The original Porsche Panamera wouldn’t arrive until 2009. Strapped to a dyno, the VW-powered M5 delivers 480 horsepower to the wheels. Factoring in drivetrain loss suggests an output of around 530 hp at the crank, a significant jump over the original BMW S62 engine, a 4.9-liter V-8, with 394 hp. The 5.0-liter S85 that went into the M5 E60 was rated at 500 hp.
It’s unclear how or why VW allowed such a unique engine, estimated to displace 5.0 liters, to end up in private hands. We know that this M5 remains rear-wheel drive with a six-speed manual gearbox, making it an absolute riot to drive. However, the absence of stability control and anti-lock brakes means that it’s probably a handful, to say the least.
The engine was apparently a fusion of two 2.5-liter VR-5s, but unlike traditional VR engines, it featured a cast aluminum block instead of iron. Surely, Piëch must have had a specific car in mind when he green-lit the project. Perhaps something from Bentley? Rumor has it that VW poured a staggering €2 billion into developing this M5 test mule. Yet, despite the massive investment, the W-10 never found its way into a production car. We’ll never know whether the engine would’ve been more reliable than BMW’s notorious S85, which also powered the M6 E63/E64.
It is believed that Piëch was so fond of the custom M5 that he used it as his personal ride to work. The late VW supremo appointed Sabine (Wolfram) Willeke to lead the development team as part of a broader project that also included the W-8, W-12, and W-16 engines. The German automotive conglomerate is no longer making W engines. The Passat’s W-8 was retired some two decades ago, while the Continental/Flying Spur’s W-12 was discontinued in 2024. As for the Chiron’s mighty W-16, it had to make way for Cosworth’s V-16 in the Tourbillon.
Source: Drivetribe / YouTube