For example a few of the Saturn “S” cars have a specific sized fastener that holds on the window glass. The design is the same as with some other GM cars but Saturn’s is a specific size. Thank goodness that Equalizer has them available otherwise you would have to take the car to the dealer to change the window regulator.

The other interesting thing is how they have changed over the years. For example, the section on alternator repair in the 1964-69 (IIRC) manuals gives you a detailed explanation of how to actually troubleshoot and repair many potential problems with the faulty part. The 1984-89 manuals tell you how to remove it and how to replace it with a brand new part from the factory. And yeah, I spent way too much money on repair manuals.

I even heard a few years back that starting from the 996s, if the engine goes bad then the dealerships don’t fix it themselves - they just crate it up, send it back to the factory, and swap in a new one.

Doing the timing belt on an Audi 2.8 V6 requires at least four or five special tools to lock cams in place, lock tensioners down, etc. Rental is ~$50, IIRC. Though at least on that engine, you tension belts with a torque wrench on the tensioner.

Zee Germans really love zee special tools, though BMW seems to be a little less prone to this insanity than VAG and Porsche.