We've spotted several camouflaged BMW M4 test vehicles in recent months. With the sightings are rumours that the CSL moniker will return, and that's supported by tweaked aero packages on these prototypes. Camouflage likely hides carbon fibre bits for a weight reduction, but when all is said and done, we still don't know if it's a legit CSL or some other special edition M4.

Now, a new rumour from the forums at bimmerpost.com says yes to the CSL. A forum member with the username ynguldyn recently shared a post claiming the CSL would enter production in July 2022, but that's not the big news. Along with the date comes word that the CSL will see a very healthy power boost to 540 bhp (403 kilowatts). As a reminder, the M4 Competition is the current performance champion with 503 bhp (375 kilowatts) so if this rumour proves true, the CSL should be quite fast indeed.

Gallery: BMW M4 CSL Spy Photos

It should also be quite a handful, as the rumour also claims it will be rear-wheel-drive only. Actually, that makes complete sense for a CSL which traditionally has been all about a lighter, more focused track weapon. As such, a manual transmission would seem likely but the rumour says it will stick with an automatic. Our prototype sightings at the Nürburgring corroborate this, as we hear seamless shifts that you'll only get from a performance-oriented automatic gearbox.

We must stress that these are just rumours at this point, as there's nothing official from BMW on the subject. However, the Bimmerpost forum member responsible for the information is a veteran member who's shared good information in the past. We know BMW has something coming for the M4 above the Competition, and the information does match up with other tidbits we've heard.

Still, we still find ourselves a bit hesitant with that power rating as it's quite a hefty jump to combine with a strategic weight loss. However, this is one of those times where we'd be very happy to be wrong.