I'll be buying a set of their covers for the non sport, convertible E46 I got for my mother. Reviews are mixed as far as TIGHT fitment.No reports of the covers NOT fitting, just reports of them being tight.
I am familiar with hog rings and reapplying seat covers did it a bunch at the Jaguar/Land Rover dealer.
might ask them if they would make them without the sewn in piece on the bottom cover to match the Z4M seats.
Rocky Mountain Raw