Spy shots and video of possible BMW M4 CSL

BMW M engineers are testing an extreme version of the already hardcore M4 GTS at the Nürburgring and on some of the German race track’s surrounding roads.

It’s impossible to say whether this is a new model in the works or just some routine testing of components, but there’s been confirmation from M boss Frank van Meel that hardcore, track-focused models are coming—complete with CSL badges.

“CSL [will be] the top-of-the-line track tool, made on the track for the track, just with a number plate,” he revealed during the 2017 Frankfurt auto show.