While I agree that based on my credit line w/ Amex I could technically charge the entire price of the car, no BMW dealer here in the states will allow you to do it. Optherion is spot on that the fees cut into the profit and that dealers will limit the amount they will allow you to charge.
2011 Space Grey E90 M3, DCT, Comp. Pkg.
1997 Z3 2.8, Artic Silver, Tanin Red interior, MT
1974 2002tii, Inka, MT