BMW M has quite the secret dungeon. In it are countless weirdly awesome prototypes that the bigwigs in Munich never had the courage to sell. Cars like an E34 M5 Convertible, an E39 M5 Touring, and an E46 M3 CSL with a V-8 all lurk in the underbelly of the M Division’s secret lair. Okay, so it isn’t much of a secret anymore, since BMW keeps showing off what’s in there, and its latest tease of what could have been is this: an E60 M5 CSL that could have been the coolest sedan BMW ever made.
A few days ago, BMW M posted a slideshow on Instagram of the M5 CSL, with a cute little teaser format, daring you to swipe over to the next picture. Each one shows off a different angle of the M5 CSL, and it’s admittedly a little odd to see a sedan wearing the CSL livery. Especially so on the E60, as it was never the most graceful looking BMW sedan. Still, it’s awesome to see and BMW should definitely apply that livery more in the future. Oddly, the second photo in the series seems to show a classic Mercedes 190 SL lurking off to the left side, just out of focus. I could be wrong of course but those bulging fenders look awfully like those of the 190 SL.
Anyway, it’s the last slide in the set that you want to see, as it isn’t a photo but a video that includes the glorious start-up and rev noises of the M5 CSL’s V-10. For CSL-duty, BMW took the normal E60 M5’s 5.0-liter V-10 and stroked it to 5.7 liters, bumping its output to 630 horsepower. It’s the sound that gets you, though. Its start-up bark is deep but it screams as the needle climbs toward its astonishing 8750 rpm redline. That’s almost 911 GT3-levels of revs but in a four-door sedan with a big trunk.
Can you imagine what this E60 M5 CSL would have been like if BMW actually put it into production? It would have been one of the most unique super sedans in the world. There were V-10-powered four and five-door luxury cars, like the Audi RS6 Avant of the time. But that had two turbos and never revved anything like this M5 CSL. It would have felt like a racing engine in a sedan and could have set a precedent for future CSL sedan madness.