I have 5% on the back window on my old ram and it is hard to see out you can't see anything unless there is a light behind you. If you open the windows so the spots where it's doubled up its hard to see even with a light behind you. I had my mom drive it and she almost hit one of our friends because she couldn't see them. That was without it doubled up. I mean you seriously would have a very hard time seeing if a person or car without lights on was behind you. It looks great from the outside though.

 

Learning to use side mirrors help. Tow something for a while it gets easier. Look around before getting in and backing up.