2012 Buick LaCrosse Owner Manual - Page 446

10-108 . Vehicle Care Removing and Replacing the Floor Mats Pull up on the rear of the floor mat to unlock each retainer and remove. Use the floor mat with the correct side up. Do not turn it over. Do not place anything on top of the driver side floor mat. Use only a single floor mat on the driver side. Do not place one floor mat on top of another. . . . Reinstall by lining up the floor mat retainer openings over the carpet retainers and snap into position. Make sure the floor mat is properly secured in place. Verify the floor mat does not interfere with the pedals.