Trees can provide shade for your parked car. However, if you've left your car under a tree for a long time, you may find it covered with tree sap when you come back to it. Tree sap can be particularly difficult to remove from windshields, as it generally will not come off in a car wash or with regular soap and water. Use special products that will dissolve the tree sap without damaging the windshield. Do not use metal scrapers that will scratch the windshield.
Rub the tree sap with a cloth soaked in nail polish remover. This will gradually remove the tree sap. Use a white cloth so you can see the sap transfer to the cloth.
If the tree sap is still visible, rub it with white spirit.
Alternatively, add just enough water to 1 tbsp of baking soda to make a thick paste.
Gently rub the paste into the windshield with a clean cloth to remove the sap residue.
Rinse the windshield with clear water, and dry it completely with a clean and dry cloth.