My sports car has similar spots all over it when I bought it. They came from some type of a tree the PO had parked under. I tried every product I could think of to get the spots off the paint and nothing worked. A professional auto detailer was able to get the spots off the paint using a product called, "Glaze Distributing Co.- Tree Sap Remover". I had tried other brands with no effect. Unfortunately, the spots were stained into the clear bra, so I had to replace it. I only mention this because I think it is likely you will not be able to get those spots out of the plastic window if it's the same stuff I had on my car. The tree sap remover did not damage my clear bra and may be safe for a window, I can't say for sure, but it may be worth a try.