I once owned a E85 3.0 and it had side skirts, quite subtle but looked great. Did M models not come with side skirts...im sure from memory they where actually called M-Skirts at the dealer. Was the skirts an option on the M?
To my knowledge the side optional side skirts were part of the Aero kit. They were no lower than standard but had a subtle ridge/line high lying the curve of the door. Similar to the ridges on the M bonnet.
Being part of the Aero kit I don’t think they were an option on the M unless added aftermarket.