I find it a bit odd that BMW comes across portrayed in this thread as take it or screw you....basically that's been said. I haven't seen this from BMW. The local dealer owner has a lot riding on his reputation. BMW corporate may try to hide and say "we'll just replace you." however some dealers expecially in smaller markets can really get burned by this attitude.
I've heard of BMW taking care of it's M5 owners with taking care of payments with 5 series as their loaners. The "Flagship" customers IMO, and I've seen this in action do get attention and they dealerships do make an attempt to help the customer. If someone wants to get arrogant, it only takes a couple letters from a lawyer to make things firm up a bit.
It's all in the realationship with the customer. I think most dealers keep this in mind. If you have a cusomter on average that buys or leases 1 or maybe even 2 cars a year is taken care of. Large markets that have 3+ BMW dealers might have a bit of a hubris complex, but in smaller towns it gets around how your service and sales are.
Small markets, such as areas with 150-200K populations or less, and extrapolate that to those that whom can afford BMWs--these are customers that are both loyal to the dealership on end, and the dealership is loyal to them. A dis-satisfied customer can have a large effect.
I do feel in some areas of the country that "Flagship" customers do have a standing. Run into a few people at the grocery store, and just a conversation starts up about cars--the information moves fast.
I've had pretty good luck with BMW compared to my other German cars. In my area, the closest Lexus dealership (yuck) is about 70 miles away. They'll pick up and drop-off your car with a loaner while it's being serviced. Maybe larger centers can say "meh" to customers, but if you do buy cars often, they do pay attention.
I have great service from sales, to service, to parts. I think these guys and gals (and a lot of BMW dealerships) do care about their customers and don't write them off as "too bad."