I'm only familiar with Pledge as being a furniture wax, not a cleaner. Yes, you can use it to clean the fine dust you'd find on furniture but not on plastic.. I would suggest you clean the window with soap and water, dry it with a soft cloth and if you wish apply pledge as a water repellant. It won't repel mud, dust, dirt and bugs (might keep them from sticking too well). Plastic scratches very easily, seems like it will scratch on its own.