Yes, unDummy, I read your posts and think you talk alot of sense about transmissions and differentials.
Just reacting to this broadside about typical BMW drivers not knowing even how to open the hood. My experience (and admittedly we aren't talking about a particularly large fleet of cars) is that guys driving BMWs out of warranty more often than not have a DIY attitude on basic maintenance of their cars, but let the local German auto specialist shop or dealer handle more complicated stuff.
Most people, no matter what they are driving, just don't take an active interest in automotive maintenance. I know I didn't as a kid growing up. My stepfather was not interested, and I just never learned. It wasn't until I got out of college and started to buy cars and pay to maintain them that I got interested. Nothing like getting hit in the wallet to arouse a person's interest. Excpet for your house, cars are the most expensive thing you ever buy and have to keep up.
Thinking about my family, relatives, friends, and coworkers, I don't think anyone other than my father-in-law could tell me when was the last time they changed their differential fluid or transmission fluid. None besides him could probably tell you what kind of engine oil is in their cars. He has a new Honda CRV.
All the others I'm thinking about drive cars from beaters all the way up to pretty expensive cars. Near as I can tell then just drive them until something breaks. I see no overall pattern in the broader population between what they are driving and how dilligent they have been maintained, either.
For every 10 guys driving a (fill in whatever car you want) neglecting it, there is 1 doing it the right way. I just sort of disagree that this is something peculiar to BMW.