To close the thread here.. just got my M3 back from a day in the Tesla Service Center. At checkin they thought it might be a gap between the trunk and the tail lights, and that's exactly what they replaced...
No it does not seem to be the lights as they are below the line of the boot lid. The water is inside the lid/door.So is the problem the seal for the tail lights?
I worked at a pre delivery center in the 90s and all the Jags had to have the tail lights removed and sillicone applied to stop water leaks into the boot and condensation in the lamps. Bodgery. Lol.
Ratcliffe road, south Leicester area?, south Knighton area is where i am. If you do see me "BS19 reg" south leicester feel free to come have a look I think there is also anther Black M3 around me somewhere but only seen it once.David - slightly off topic but is it your black model 3 that has been parking in Ratcliffe recently? I've driven past it a couple of times and have been itching to have a closer look and a word with the owner
Although i have not noticed it lately, i had my boot lid re-seated by the SC and this seems to have helped