I've used a product called "Goof-Off" with good success, works best on "gummy" type stuff left after the sticker is removed, might eat the stickum under the edges of those Govt stickers a little at a time.
Can damage certain paints, but my experience says OK for most automotive-type finishes, try in inconspicuous place first.
Can damage certain paints, but my experience says OK for most automotive-type finishes, try in inconspicuous place first.