Fast Car

1. Purchase the correct replacement filter. BMW uses a charcoal activated filter for its 3 Series. You may be able to purchase an aftermarket substitute at an automotive parts store, but you can purchase a factory replacement at your BMW dealer.
2. Shut the engine off and pull the hood release. Locate the cabin air filter cover in the rear part of the engine compartment, right beneath the windshield (it extends to the width of the engine bay).
3. Twist the three fasteners counterclockwise to unhook the cabin air filter cover. Once the fasteners are loosened, pull the entire cover up and set to the side.
4. Pull the old filter out of the compartment. Its clearly visible with the cover removed. Inspect the compartment for foreign items and debris; remove them, if applicable.
5. Insert the replacement filter into the compartment. Position the cabin air filter cover back in place and turn the three fasteners clockwise to secure it.

1. Remove the cowling cover from rear of the engine compartment that covers the firewall. The cowling is secured with screws to the frame of the vehicle. Use a screwdriver to remove the screws and set the cowling off to the side.
2. Locate the cabin air filter compartment on the left side of the firewall, next to the heater fan. The air filter is 6-by-9 inches in size and 2 inches thick. It should be mounted vertically against the firewall. Remove the cover by using a screwdriver to lightly unfasten the lid.
3. Remove the cabin air filter from the compartment. Clean out the compartment by vacuuming out any dust. Wipe it down with a clean damp cloth.
4. Replace the old cabin air filter with the new filter and make sure filter is seated properly. Secure the lid on the filter compartment, making sure the pins snap into place.
5. Reattach the cowling cover over the firewall with screws. Remove all tools from the engine compartment.