
I haven't owned an E28 in a decade now and I clearly remember that isn't anything even close to the original trunk seal. Now I'm not saying the original can't be improved on, I'm not really a fan of the glue in the dish mount, but I hope they at least make it clear it's not like the original.
OK, I've stopped hyperventilating. (and it's not even my car) Is it possible it's mounted in reverse? If it's symmetrical, the answer is probably no. But if it's say an upside down J or L shape, with the flange facing outwards instead of inwards, I can see how it might work, and the trunk might shut. Might.
A bit OT, there are a variety of places that sell restoration parts, including things very similar to the original E28 trunk seal, albeit without the square corners, for often very reasonable prices. Yeah, it might be intended for a '65 Dodge Dart, but if it fits, who cares. If you're a purist looking for a perfect M5 restoration, it's out of the question, but so is the above.