I put my deposit down about a year ago. (July 2005)
We have 2 dealerships in town. One took a $1k deposit with no dealer mark-up. The other told me they were not taking deposits and to expect at least a $10k mark-up. So it is hard to say what dealerships will do and I have bought 4 BMWs new and 1 pre-certified (3 of the 5 being M's) between both these dealerships over the past 5 years.