You know, I may have to do a DIY on how to get rid of that film as many folks complain about it.
Here's the deal. You can clean it, but it will return. I have no leaking heater core or smoking going on inside my ride so I know that this is not the issue. It just happens over time and there's nothing you can do about it. The key is knowing how to clean it. Here's the trick.
First, you must start with either direct sunlight or extremely bright lighting shining through the windows. The first thing you do is take a microfiber rag and liberally spray it down with a window cleaner of your choice. Windex will work just fine. You can use the medium quality microfiber towels that you find in bundles at Auto Zone, Pep Boys, O'Riley's or the such (these places don't sell high quality microfiber towels, I don't care what anyone tells you or thinks). Throughly clean the windows. Your microfiber rag should be good and dirty when you finish. The key is getting enough Windex on the towel in order to remove all of the surface dirt. Once you finish, that rag should only be used to clean your hands or something similar. Do not use it on the car again.
Next comes the hard part. When you look through the window into direct sunlight or lighting, you should see a ton of streak and smears. Basically, the window will probably look like crap. Here's where you break out a clean microfiber rag and start buffing that window clean. As you start rubbing the window, the rag will hang up a lot. It will basically make you sweat as you try to push it through the smears and streaks. As you continue, you will notice that the window will begin to get very slippery. This is what you're looking for. You want that window to get as slick as possible. You are not using anything but a clean microfiber rag. No solvents whatsoever should be used during this process. Work only on a section of the window at a time. As you do a section, inspect it by looking directly into your light source through the window. You should notice a distinctively clean window, that will now probably reveal all of the scratches and swirls in the glass (that's a whole different DIY). Next, move on to the another section of the window.
The tell tell sign that you're getting the window clean is when the rag quits hanging up as you wipe the window. If the rag does not stop hanging, then you didn't do a good job cleaning with the Windex. Repeat that step and then start the dry buffing process again. Once the rag no longer hangs, that window is damn near spotless, if not spotless. Look through it and be amazed.
