i had a similar problem when i got my x5, but i found out that all the bmw dealers get different rates and options from bmw financial center, and it has alot to do with how much the stealer sales and so on....
when my brother and i when looking for his x5 we were able to get 2.9% this was back on 09/04, and them 2 months later i got my x5 and they were trying to give me 4.9% so i asked why not 2.9% like other dealers and they xplained to me how it works, so i told them that i didn`t care that i wanted a better rate, so the manager called me into he office and got on the phone with bmw financial center and asked them if they were going to let them loose the sale, so the bmw financial center manager told us to wait by the fax machine for the new paper work with the new rate 3.9% so i took the X5