Originally Posted by NathR

Classic Additions DO do custom outdoor covers as mines currently sitting under one. My Dad also had them do outdoor AND indoor tailored covers for his FRS, M3 and Z3 M Couple.

The one mentioned isn't tailored to your car, thats just their best fitting universal one.

Being breatheable they do let a bit of water through but they're designed to be like that to prevent other more serious problems apparently.