I ran out to the car and upset my morning coffee routine for this so that 318 better be the same as my 325
First lift the cupholder part up at the rear, then slide it back. It's just held down with velcro. Pull out the rear ashtray. Then stick your Phillips screwdriver through the holes indicated by the arrows on photo right, and undo the screws. The e-brake boot just snaps off around the edges.
Shame on you wasting a good root beer
Shit . . just realized some E36's have an armrest, someone else will have to help you with that part.