Stickers can be a great way to express yourself and decorate your vehicle, but unfortunately, they can be problematic as well. After you've removed the sticker, leftover residue from adhesive can leave unattractive grey gunk spots on your windshield that are tough to remove. Fortunately, there are a variety of ways you get rid of that gunk using household materials.
Remove all large parts of the sticker that can still be easily pulled away by hand. These bigger chunks will make things more difficult during the next steps if you don't pull them off now.
Scrape. Using a plastic scraper (not metal), remove as much remaining residue as you can. For best results, use a scraper made of firm, slightly flexible plastic with a sharp edge. Many kitchen serving utensils work well. An old credit card can also be used for close-up work.
Use an orange oil-based cleanser specifically designed to remove sticky messes. One such product that's highly popular is called Goo Gone. Avoid products that contain a sandy, abrasive element that could scratch the windshield.
Use an abrasive plastic scrubbing sponge, like the kind used for washing dishes. Make sure to avoid a metal scrubber, as this will certainly scratch your glass. In fact, some plastic scrubbers may be harsh enough to do this as well, so be sure to test the one you're going to use on something made of glass from the recycling bin.
Use a pencil eraser. Pencil erasers work by rubbing pieces of themselves off and taking the substance to be erased with them. What they can do for pencil graphite markings, they can also sometimes do for sticker residue.
Use peanut butter. You mother may once have removed chewing gum from your hair using this handy food item, and using it to get rid of sticker goo works on the same principle. Place some peanut butter (use "creamy" for best results) on the residue, and leave it to sit undisturbed (and out of the rain) for several hours. The oil in the peanut butter will unstick the adhesive and cause it to come away from the windshield. Wash away the whole mess using water and oil-cutting liquid dish soap.