I'm not a dealership owner nor a family member. I buy 1-3 BMWs/year and I'm good friends with the GM and have built relationships with many people at the dealership. This is a simple transaction if you know what you're doing and the dealership is open to it. You can ask
@blancax3 about his experience and in this case, neither of us were charged anything.
I was at the BMW dealership this morning to sign the paperwork and the finance guy gave me a high five and said thanks for the deal, he probably made an easy $500 on the finance upcharge (on the interest rate) and the sales guy made a minimal commission of $250, the dealership probably made $500-1K in total but I'll be picking up my $150K i7 early next week.
Again, I have a great relationship with these guys so that's why they did this particular one, YMMV.
The Ford dealer balked a bit after they said they would do it, which is annoying after I just bought this Raptor 4 weeks ago and I'm expecting the R any time now. That said, this is my first transaction with them so there is no loyalty there.
Hope this thread is helpful, happy to answer any questions!