This may be of interest to S1 and S2 owners - I don’t know if it applies to newer cars.
There are chrome trim strips at the top edge of the door that hold the fuzzy weather strips against the outside of the window. On my car, these rotted out a long time ago and I’ve been without. Some time ago, I ordered new trims from Paul Matty, and I just got around to installing them.
The original trims (I still have one) have a horizontal channel that slips over the top edge of the door, and a vertical edge to which the weather strip is clipped. The replacements are a simple “L” section in stainless steel; they don’t have the horizontal channel. To hold them to the edge of the door, I drilled three holes (in addition to the one already on the extension tab) and screwed them to the fiberglass with No. 4 sheet metal screws. This is obviously not original but it is unobtrusive and tidy, and a lot better than the raw fiberglass edge (and no weather strip) that I had before.
I also ordered the trim strips that sit on top of the door panel inside the window. On my car, these are heavily pitted but serviceable. If anyone has a source for these I’d like to know.