Don't use gasoline, xylene or acetone. Really no reason to endanger yourself. The acetone makes a pretty good powder coat stripper anyway.
As others have said, heat with a hair dryer. Warm them enough so that you can peel up a corner and then just keep the sticker warm ahead of where you are pulling it off. Not enough heat or pulling to fast and the sticker will rip. Too much heat or pulling too slow and the sticker will stretch and break. You will figure it out.
The VERY BEST remover for adhesive without affecting any paint or plastic that you want to protect is VM&P Naptha. You can get it at the local hardware store. A gallon of this around the shop is as harsh a solvent as you will want for cleaning up all kinds of sticky residue, tar on vehicles, oil residue, etc and WILL NOT HARM PAINT. it is one step harsher than Mineral Spirits.
Googone works great too. It is almost exactly the same stuff but costs several dollars an ounce rather than several dollars for a quart or a gallon.