BMW M will celebrate its 50th anniversary in 2022 when the M3 CS and M4 CSL are expected to come out with more power, less weight, and better aero. The two-door version has now been spotted in busy German traffic with a surprisingly large amount of camouflage denoting some important changes over a standard M4 Coupe.

The controversial front grille keeps the same size and shape, but with new Y-shaped design elements finished in glossy black. The right kidney contains the model's designation, with "M4" and several indistinguishable smaller characters hiding under the black tape. Presumably, those say "CSL" from Coupe Sport Leichtbau (Lightweight).

BMW has also redesigned the bumper as the front fascia looks substantially more aggressive with the standard M4's air intakes now split into two separate sections. The CSL is said to usher in the first M-designed headlights, but that's likely limited to the graphics as the cluster itself appears to be identical to that of a regular M4.

It's the same story at the back where the taillights have the same shape, albeit with fresh LED elements better visible in the images showing the prototype while the test driver brakes. Also at the back, the boot lid now holds a chunkier spoiler, without looking as over the top as the big rear wing available as an M Performance option for the M4. The CSL also lacks the centre-mounted stacked exhaust tips available as an extra on the regular model, and dare we say it's for the better.

While the M4 Competition boasts an already healthy 503 bhp, it is believed the CSL will be dialled to 540 bhp sent exclusively to the rear wheels as BMW is apparently ruling out an xDrive model. Nothing is official at this point, but the hotter M4 could be an auto-only affair in the same vein as the aforementioned M3 CS. Both will get quite a few carbon fibre bits to shave off weight, with the M4 CSL likely to get a more strict diet to live up to its badge.

BMW is reportedly planning to kick off production of the M4 CSL in July 2022, meaning an official premiere could take place in the first months of next year.