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?
For one year only in 1972 Porsche moved the oil tank forward to under the right rear fender to try and improve the rear engine handling characteristics. When they did this they added a oil filler door above the tank on the rear fender. Problem was this looked just like a gas tank which caused quite a few people to add gas to their oil tank and destroy their engine so for 1973 Porsche moved the oil tank back. A few years later they tried again and moved the oil tank back to under the fender but smartly they added a long tube to the tank from the oil filler cap in the rear so it wouldn’t be mistaken any more.
The oil filler door is specifically marked “oil” and has a passenger door push rod rather than the fuel pull on the dash to the left of the column.
The driver would have to try to fill with fuel.
I believe the actual reason why Porsche changed is because the oil filler required a different quarter stamping, with a more convolute filler stamping welded to it, along with a cast lid. It was more expensive at a time when Porsche was investing in reduced production costs.
These “oil door 11s” are stupidly expensive and sought after nowadays.