Watching an episode of Chasing Classic Cars - so they’re restoring a 1973 BMW 3.0 CSi for a customer. Trying to chase down a damp sunroof liner, they suspected one of the drainage outlets was blocked. So BMW with their crazy German engineering, the sunroof drains out the rear of the side BMW badging on the C-pillars!

Made me wonder what sort of other obscure engineering details that most of us have missed in cars?