Completed this mod on my 335is. It will take about 10 minutes to remove each reflector and about 15 minutes to peel off the old adhesive. All you need is some Goo Gone, a putty spatula, and painted reflectors. Do not use a screwdriver, box cutter, or utility knife.
Working on the right side, turn the front wheel all the way to the left, away from the reflector. Spray Goo Gone liberally around the edges of the reflector both interior and exterior surface. Goo Gone can not hurt your exterior paint. If you are worried, after spraying the Goo Gone, wipe the excess off your paint with a wet cloth. Let sit 10 minutes.
Place the spatula perpendicular to the long axis of the reflector and work its edge under the front lip of the reflector and pry up. It will separate easily and now is a good time to spray more Goo Gone along the reflector's edges.
Free the bottom edge of the reflector from the thin strip of fender first. Once free, push the reflector into the wheel well and the entire thing will pop right out. Now the hard part. With your bare fingers, pill-roll the old adhesive off the inside of the fender. This is time consuming and requires patience. Clean fender surface with soap and water and let dry.
Peel off the backing and place painted reflector and press firmly.It will adhere immediately and strongly so do a trial fit first with the backing still in place. Voila! Hope this helps.