This Is Why Volkswagen Put a 500-HP W10 Engine In A BMW M5

When people think of Volkswagen

, they might either think of its beloved classic models or its sensible everyday cars. They might also think of some of its brilliant performance cars, such as the Golf GTI and Golf R. What quite a lot of gearheads may not remember is that there was a time when the Volkswagen Group went absolutely crazy with engine development.

The German automotive giant developed not one but two new engine layouts during the ’90s and ’00s. While some of those engine experiments did make their way into production cars, there were quite a few that didn’t. One of those crazy engines never made it beyond being tested in a mule car. Not only was this engine absolutely crazy, but the car that it was put into to test it was perhaps the most unexpected car you could think of.

Volkswagen’s Crazy W10-Powered BMW M5

BMW

Divisions

M

Founded

1916

Founder

Karl Rapp and Gustav Otto

Headquarters

Munich, Germany

Specs

GMD Motors

On the outside, this car might look like any regular E39 BMW M5. It’s not in the best condition ever, as the body is full of scratches and dents. It’s not in a particularly striking color, either. But the unremarkableness of this E39 M5 disguises something very, very cool. This one has had its BMW V8 swapped out for a Volkswagen W10. This is the only car ever to have this engine fitted. Only one other example of this engine exists, too, and it’s owned by the same person who owns this M5.

The reason it has this engine is because Volkswagen bought it to use as a test mule. When new engines are being developed, it’s common practice to install the new engine in an existing production car to test it out. There have been many famous mule cars over the years that have had this treatment. One Ford Mustang Cobra R gained some fame as the test mule for the Ford Modular V10, Jaguar tested the XJ220’s engine by dropping it into a modified Ford Transit, Ferrari developed the Enzo’s 6.5-liter V12 through a modified 348, and legend has it that Lotus once bought a Ferrari 458 to use as a testbed for an in-house V8.

VW Boss Ferdinand Piëch Used This Car As His Daily Driver

This W10 M5 project was, in many ways, as much of a personal project for Piech as it was a project for the Volkswagen Group’s engineers. Nothing showed that more than the fact that Piech used this car as his daily driver! All the dents, dings, and scratches on the bodywork can easily be explained by the fact that Piëch daily drove it for some time. It must have been a pretty difficult car to drive daily, too. It had no ABS or traction control, no working speedometer, and smelled of fuel and exhaust vapor on the inside. Perhaps Piëch liked that, though, as he was an old-school gearhead. The mule having a manual transmission was at Piëch’s insistence, as he apparently wanted the first production car fitted with the W10 to be a manual.

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Why Develop A W10 Engine, And Why Use An E39 M5?

Why would you develop a W10 engine in the first place? Well, it was part of the same grand strategy that gave us the W12 and the W16. Ferdinand Piëch devoted much of his studies to engines. His University thesis was even around designing an engine for a Formula 1 car! So, when he became the CEO (and later the chairman) of the Volkswagen Group, he put a huge focus into developing innovative new engines. This included developing the “VR” format Volkswagen already used to create compact V engines. The W10 engine was created by putting two VR5s together, in the same way that the W12 was two VR6s put together. The two engine blocks were side by side, sharing a single crank running down the middle.

There was a major advantage to building an engine this way. Thanks to the tight packaging of the “VR” engine format, the W10 could fit in a similar-sized engine bay as a conventional V8. This not only meant that it was very easy to get into the E39 M5 mule car, but it could also be put in cars that weren’t designed for big engines at first.

The BMW M5 Is The Perfect High-Performance Test Mule

Why would Volkswagen use a BMW M5 as a mule car? Well, the BMW M5 is designed from the factory to be able to handle big power. The regular factory versions of the M5 have plenty of power as it is, and BMW is renowned for developing cars that drive impeccably with that kind of power. As a result, you can take the power of an M5 up to supercar levels, and it’ll still be able to handle it just fine. That’s something that McLaren took advantage of when the F1’s V12 engine was being developed. The mule car for that engine was an M5, specifically an E34 touring with the massive V12 engine put in the trunk.

Not only is the BMW M5 capable of handling a lot of power, but it also looks very discreet. To most people, it would just look like an ordinary BMW sedan at first glance. You could drive right by them at regular speed, and they wouldn’t suspect that some kind of crazy engine is hiding under the hood (or, in the case of the McLaren mule, in the trunk!). That, combined with its ability to handle big power with little to no modifications, makes it the perfect car to disguise a secret engineering project.

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Why Aren’t Volkswagen’s Crazy Engines Around Anymore?

The Volkswagen Group was once a bastion of weird and wonderful engine layouts. VW could sell you a Golf that had a VR4 or a VR5, the VR6 was one of its standard engines for decades, and we can’t forget about the glorious W16 that powered Bugatti’s Veyron and Chiron. But, these engines have all disappeared now. The Bugatti Tourbillon uses a Cosworth-developed V16 instead of a new version of the W16, the VR-engines have all been retired and even the W12 finally bit the dust in 2024.

Why has this happened? Well, there are a couple of reasons. In the case of the W12, Bentley wanted to get rid of it because of emissions targets and its plans for electrification. Bentley aims to become a fully electric brand by 2030 as part of its “Beyond100” strategy. The W12 engine couldn’t really be hybridized to keep it going right up until that 2030 cutoff point, and its thirsty and polluting nature just didn’t line up with the brand’s new ultra-sustainable strategy. So, unfortunately, it had to be retired.

Bugatti also cited emissions regulations and electrification as reasons for dropping the W16. This seems somewhat ironic, considering what powers the Tourbillon! But, the Chiron’s successor wasn’t originally planned to be powered by an internal combustion engine. A low demand for fully electric supercars changed Bugatti’s plans.

Would A W10-Powered Luxury Sedan Have Worked?

Developing an engine as impressive as the W10 is very cool. But would there have actually been a good use for it? That’s a question we can’t definitively answer. Because the W10 never made it beyond being put in that BMW M5 mule car, we don’t really know what it would have ended up powering. Since an M5 was used as a mule, it was likely being developed to be put in a car to compete with it.

DriveTribe’s Mike Fernie speculates that the W10 could have been used in an R model of the Volkswagen Phaeton. If it had ever been made, it would have likely appeared sometime during the ’00s and competed with other high-performance luxury sedans of the day. Considering how hard the Phaeton flopped, though, it’s unlikely that a speedy R model with a crazy 10-cylinder engine and a manual transmission could have saved it.

Source: GDM Motors.