Over the past few years we have been treated to a ton of BMW M products, a lot of which have been fairly special such as the CS variants of the M2 and M5. But one designation that we have seemingly been waiting forever for is the return of the revered CSL badge. Before anyone from within BMW confirmed the CSL's revival, a plethora of test mules have been spotted of BMW M4 prototypes sporting styling enhancements to the grille and aerodynamic packages.

In recent months, BMW has let slip that a special model is in fact in the works to celebrate M's 50th anniversary, and the M4 CSL may have even been cleverly hidden in plain sight in a recent video to mark the occasion. But now we have word on when the M4 CSL will be revealed.

According to a report from BMW Blog, it looks like the reveal of the BMW M4 CSL is just around the corner as both the M4 CSL and the M3 Touring will officially break cover this May. This coincides with the division's 50th anniversary around which time we anticipate a monumental celebration.

When the CSL arrives, what can we expect? According to the ex-head of BMW M, Markus Flasch, the Coupe Sport Lightweight designation will be a reference to the proposed weight reduction of 220 pounds. This will be achieved by the removal of the rear seats and other seemingly unnecessary trimmings.

Up front will be an uprated variation of the S58 twin-turbocharged 3.0-liter inline-six engine that is expected to produce upwards of 540 horsepower. In a bid to keep performance to the maximum, the CSL will be built exclusively with the M Steptronic torque converter automatic gearbox and only adopt a rear-wheel-drive configuration.

Visually, the M4 CSL will be substantially more aggressive as it incorporates a fixed front splitter and ducktail rear spoiler. To keep the mass low, it is understood that a generous amount of carbon fiber will be utilized inside and out. There's no word yet on details like production numbers or pricing, but rumors already abound that something even more hardcore could be in the world with a manual transmission. Time will tell.