Selling price could be better, you have another $1k wiggle room to play with.
They should be able to do that car for a selling price of $50,941. Why didn't you go with 36 months?
Let me give you a quick breakdown
MSRP = $57,195
Invoice = $53,191
Selling = Invoice - $2250 (holiday credit + loyalty) = $50,941
10K miles - Residual 62%
MF - .00125
$596.81 a month - Bank, DMV, 1st month due at signing (~ $1500)
$637.66 a month - Sign and drive $0 due at signing
2015 X6 White/Red ZMM,ZDA,ZDB,ZPP,337,4U1,688