USB was an option (6FL actually), however, the AUX port was standard in LCI models. You should have an AUX jack either in the glove compartment or on the back side of the armrest under the vents for the rear seats.
2014 535i - MSport, HUD, NAV, Prem, Surround View, Driver Assist
2008 550i (R.I.P.)
2005 530i - Prem, Sport, NAV
2006 Jeep SRT-8
2003 Infiniti G35 coupe