Some time ago one of the users on a norwegian BMW board posted an image of a switch underneath the rear seat of his M5 converted 535i, wondering what it could be for. He says he thinks it's being pushed down by the rear seat, and he's tried pushing it down without noticing anything anywhere. He's also tried following the cables with no luck (disappears together with a bunch of other cables). There's been lotsa creative suggestions, but I don't think we've figured out the mystery of the switch yet. I and several others have checked the (BMW) part number in ETK with no match.

Here's a picture of the mysterious switch:


Here's the original thread, but it's in norwegian:
http://www.bimmers.no/viewtopic.php?t=10638

Is anyone here able to tell us what it's for? We're dying of curiousity..