The secret BMW M6 CSL was the first - and only - M car to get active aero

Imagining this E63-generation BMW M6 goes hand in hand with the E60 M5 CSL you've just been reading about? You’re right of course. With the E60, M experimented with the drivetrain and chassis. This one did something much more interesting, something that – to this day – BMW has never fitted to any M car.

Active aerodynamics. On the back deck of this unassuming maroon 6 Series is a pop-up wing. Set back behind the front bumper is a drop-down splitter, reducing airflow, lowering pressure under the car and increasing downforce. They’re controlled by a pair of switches on the centre console that plainly aren’t in keeping with BMW’s material quality and design of the time. The next step could have been to do away with the physical buttons, make them speed dependent.

M certainly seems to have purged buttons – and pretty much everything else – from the door trims. Lightweighting was taken to new levels here, almost everything was stripped off, the window switches replaced at an almost unusable angle, a door grab roughly bodged. Close the doors and check out the low profile exterior mirrors with their reduced frontal area. You can’t see much in them, but the DTM vibe is ace.

BMW today makes no claims about the downforce or aero effectiveness of this M6 CSL study – although it’s perhaps telling they’ve yet to dabble a toe in active aero on any car. Under the bonnet this car sports the same uprated 5.4-litre V10 and twin clutch DCT transmission as the M5 CSL, complete with that fabulous carbon cover over the engine and intakes.

Now throw all this together and just imagine. 550bhp naturally aspirated V10, twin clutch gearbox, over 100kg stripped out, active aero, 0-62mph in the low fours, top ends of 200mph and 8,500rpm. That was a ripper wasn’t it?

Photography: Philipp Rupprecht