BMW published a new video from its museum in Munich, highlighting the special exhibition for the BMW M’s 50th anniversary. In typical BMW fashion, the video shows interesting prototypes from the “secret garage”, including a one-off M5 Convertible, a V12-powered Z3, and the unique M8 with its engine sourced from a Le Mans racecar.

As we all know, none of the three vehicles was greenlit for production, but BMW engineers built fully functional prototypes and kept them well preserved.

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Starting with the M5 Convertible, it is two-door, soft-top variant of the M5 E34 from the ’90s. Mind you, this generation of the M5 was only available in four-door sedan and five-door Touring bodystyle variants, so building a Convertible wasn’t an easy job. The vehicle comes with a four-seater cabin featuring custom seats with integrated seatbelts, a large boot with space for the retractable roof, and several bespoke bodypanels. The underpinnings are shared with the regular M5, including the 3.8-liter inline-six engine.

The next cool prototype looks like a regular Z3 M Roadster, but it hides something really special under the bonnet. BMW engineers took a 5.4-liter V12 from the 8-Series and stuffed it in the RWD roadster. The prototype was described as “overkill”, with a less-than-ideal weight balance, although the brutality of the V12 power makes it remarkable. The prototype was built in 1999 and has made a few appearances before.

Last but not least, the glorious M8 prototype is also present in the exhibition, showing what could have been if BMW decided to offer a full-blown M variant of the 8-Series. The red-painted prototype with the unique bodykit including side intakes and sportier bumpers was recently detailed in another video. Under the bonnet lies a tuned 6.0-liter V12 with dry-sump lubrication that served as a base for the Le Mans racecar. Interestingly, the fuel tank is mounted at the trunk since the packaging was quite tight.

The video also gives us a brief look at other cars from the exhibition including a gorgeous BMW 3.0 CSL racecar and the first M-badged 5-Series. Visitors at the BMW Museum will be able to see them in the flesh, taking a good idea of the history of BMW M.