The window slides down into a very tight spot. Be sure to get thin film. Once I got thick film, and the tint scraped easily because of all the dirt that was trapped.
Yes! Metalized films will degrade AM sound quite a bit. It is better to go with a dyed film on the rear window. Also, when you install window tint on the rear doors make sure the installer install "eel skins" which is a felt material to keep the window film from scratching. Mercedes uses a really hard rubber seal on the rear doors and chances are they will scratch the film if precautions are not taken!