Just kidding and a fair question. I believe that many if not all of the BMWs have the battery in the trunk area. I was told that the battery is under that small storage compartment in the rear center area of the trunk and you have to unscrew the two fasteners. If you check the engine compartment you will find two large metal studs for both the positive terminal (RED) and negative terminal for making external connection to the car. If I am in error someone jump in.