You need to make a solution with ½ cup of water mixed with 1 tablespoon of salt in a bowl. To this you should add 1 teaspoon of bug spray and then 1 tablespoon of rubbing alcohol. Mix all these together until the salt has completely dissolved.
The last road trip we went on, a passing semi truck hurtled a rock and chipped the windshield on the new car. I almost want to try to find some auto glass replacement center that sells bullet proof glass for windshields. Replacing and repairing glass is important, since large cracks in windshields can get you ticketed.