If you have a 2002 BMW 325 Wagon, it is in the rear compartment on the right (Passenger)side. It requires several nuts to be removed to take the battery out. Replace it with a similar 8 year warranty battery. They are very heavy. Also, be sure to connect the breather tube to the battery so it can vent to the outside of the car. Battery is located inside the car, the small breather tube allows it to vent outside the car. Do this or you will have battery gases inside of the car - a dangerous situation.