Have you owned a BMW? Or any "luxury" brand? I personally haven't to be able to speak of any "perks". I know people who have, and depending on the dealership, really weren't treated any different than most non-luxury brands, once the sale was completed. At least around here. Most dealers off some form of loaner vehicle option. The one CDJR dealer has a "loaner" fleet, but it's just Enterprise rentals that the dealership controls and slaps their logo on. You have to fill out rental paperwork and everything.
Yes I have.
I owned an Infinity G35x and have been at the dealership a few times with it, it wasn't purchased new, but I believe it's sticker price was 75k.
They damn near treated me like royalty there, is was actually kind of weird. A lot of their customers were older men and women (70+).
One time I was there getting control arms looked at, it needed lower control arms if I recall (but I could re-use the bushing or whatever it was) and I had a quote for around $1500 from them and I said there was no way I was going to pay that and I would just do it myself as I could get the parts way cheaper not using OEM.
They grabbed the tech that was working on my car and took me in back and lifted my car and showed me exactly what needed to be done and gave me some tips and pointers for doing it myself know for a fact I wasn't going to pay them a penny.
Other dealerships wouldn't even let you in back let alone actually give you tips or pointers for quirks of your car especially after saying you aren't spending any money.
I have a few friends who are essentially meatheads and own or lease BMWs and they can't even tell me how many liters their engine is or what kind of oil it might use and they get very similar treatment at their dealerships.
I can't say for sure why the luxury brand dealerships around here give exponentiation better services and perks, maybe better kickbacks from the manufacturer but around me it's night and day when it comes to "regular dealerships" and "luxury"-
I don't think the value is there for the luxury brands anyways regardless of perks, I do my best to stay OUT of the dealership unless I am buying a new car also.