alex,
most bmw will have an extra wiring near the center console , but in order to use this outlet, you need to have specific wiring harness for that particular model, i.e. e30m3, e36,e39,e34 etc,etc, the harness from the gearknob is universal, its just the extra set that connects from console to gearknob harness
else just add your own wire harness and tap it from the cigarette lighter/stereo/window switch