If you’re a genuine car nerd, this might be most fascinating car headed to auction this year. It’s a unique piece of automotive history, owned by one of the most important automotive figures of the modern era, and a mashup of two giant German brands. Broad Arrow will auction this E39 BMW M5 on October 9th, and it isn’t any ordinary M5. It was the daily driver of Ferdinand Piëch when he was CEO of Volkswagen, and is powered by a prototype W-10 engine.
In the 1990s, Piëch was toying with Volkswagen’s VR engine design to create large but compact engines. The VR6 is unique, because it’s a narrow-angle V-shaped engine but only uses one cylinder head. The angle of the V is so narrow, and the cylinder spacing is such, that all of the cylinders are in one bank, making it simpler than a traditional V-6 and more compact. Piëch wanted to make bigger engines with the same idea, which is how the Bugatti W-16 came to be, using four banks of four cylinders but only two cylinder heads. In a way, Bugatti’s W-16 is just two VR8s. However, before Piëch’s team created the W-16, they built a prototype W-10 and needed something to put it in.
At the same time, Piëch wanted the VW Group to make an M5-rivaling sport sedan. So why not test the prototype in what was, at the time, the best sport sedan in the world? So Piëch had the W-10 stuffed into an E39 M5, and he used it as his personal car for testing. Only three of these prototype W10 engines were ever built. One is in this car, another actually comes with it on a stand so the new owner can check it out, and the third is in Germany somewhere, likely locked in a secret VW vault.
That monster W-10 made 473 horsepower and 437 lb-ft of torque, and is paired to a six-speed manual. While everything under the hood was custom designed, like the air intake and cooling system, this engine has been in use ever since and continuously maintained. Since VW did go on to make W-8 and W-16 engines, it’s said to have been serviced using VW catalog parts and its most recent service was in 2025. The current owner has had it for about 10 years, registered in Slovakia, and has been driving it regularly. There’s no telling how many miles are on it, as it doesn’t have a proper odometer, but it looks to be in pristine condition.
From the outside, you’d never know this was anything other than a stock 2000 BMW M5. Well, as long as you don’t see the stickers that say “Prototype W-10 engine running in BMW M5.” Other than that, it looks like a normal Carbon Black E39 M5. Inside, its black interior and wood trim are almost entirely stock. The only differences are the custom Stack semi-digital gauge cluster and center console gauges with a red kill switch. It was a prototype, after all.
Broad Arrow estimates that it will sell for somewhere between 250,000-350,000 euros, which seems like a steal to me. This is a genuine one-of-one E39 BMW M5 project car powered by a prototype Volkswagen engine, spearheaded by an automotive legend, and whose engine was the precursor to the mighty Bugatti W-16. Whoever owns this will have something not even the richest people on Earth can buy. And it’s also probably incredible to drive.
