So you're trying to sell your car and suddenly having that bumper sticker that says "Lost your cat? Look under my wheels" doesn't seem like such a good selling point. Here's how to remove bumper stickers without damaging the painted bumper underneath.
Step 1
Find a powerful hair dryer or rent a heat gun.
Step 2
Hold the hair dryer about 6" from the sticker and blow heat directly on the sticker for a minute or two. If the corner of the sticker does not start to lift try longer. OR, hold heat gun from sticker from 8" - 12". This works much faster than a hair dryer.
Step 3
Starting at a corner, with your fingernail (or razor blade to grab the edge only) peel back a corner. Do not pull directly up. Pull back, folding the corner over against the face of sticker.
Step 4
Pull slowly by the corner of the sticker in the opposite direction and continue to apply heat as needed.
Step 5
Once the sticker is off, clean off remaining adhesive with an automotive adhesive cleaner such as PPG Ditzo DX 440. You may need to re-apply wax to the area.