What is the best product for cleaning car windows without streaking?

There is one common, low cost product that most people already have at home. Dish soap! Mix a small amount of dish soap into a spray bottle of water. Spray the solution directly onto the window and wipe with paper towel. Alternatively, you can use an old microfibre cloth that has been well wrung out. The glass will be clear, the streaks will be gone, and the windows will be sparkling and clean.