You are correct, of course, but I think the majority of that would go away if you hired the mechanic yourself and bought parts direct. My theory is that most of the German luxury vehicle surcharge is the "hey, it looks like you've got money, how about you give me some of that" surcharge.

I mean, I've owned a BMW 325is and a Toyota Sienna. Similar vehicles in that the vehicles had similarly sized engines/transmissions and brakes to match.

Sure, my experience agrees with your assertion in that rolling into the mechanic in the 325is is going to cost me north of twice what rolling into the mechanic in my Toyota Sienna will cost me.

But if you are doing the work yourself? the German car isn't any harder to work on. If anything, I think the german mechanical aesthetics agree with me in ways that make working on it easier than working on a Japanese car. Sure, they need a little bit more love in that they're just not as advanced as a Japanese car, or at least not as much effort is put into maintenance free operation, so you need to do more to keep them running, but that difference isn't huge. Parts are also not hugely more expensive than similarly specc'd parts on the toyota (e.g. brake rotors cost about the same on my 325is as they did on my toyota sienna; they were similarly sized, too; it's just the 325is was a much smaller car, so stopped dramatically better.)

I mean, I'm generalizing about German luxury vehicles from my experience with another brand, but yeah, if you hire your own mechanic, I bet most of the maintenance cost differences become much smaller.