Is this a good idea or a bad idea?
I understand the desire to have a unified front. It goes hand in glove with making all the dealer showrooms look the same. Most national chains have corporate ID standards. They are how we know we are in McDonald's and not Sears. I understand the need for national advertising of "free short stack of pancakes on this Tuesday before 10:00".
However I think BMW is making a big mistake on this. BMW has a small number of customers (compared to McDonald's) who will attend an open house. In this area we have 4 (take that North Dakota!) dealers in a 50 mile radius. Next weekend riders will have to pick what dealer they want to go to. Sure you could go to all of them, traffic is not that bad on 95 on a Saturday. Most will pick one dealer, eat lunch and hang around until the door prizes are given out then go home.
For the few hours they last a lot of effort is put into them by the dealer staff and those who lend a hand. With internet discount retailers making brick and mortar discount sales seem like less than a deal I wonder how sustainable this business model is. Seems a shame to put forth all that effort and then have compete for attendees.