AM broadcasts can be received at greater distances than FM broadcasts because AM radio waves are transmitted at low frequencies. These long, low frequency radio waves can travel lengthy distances; however, AM signals are easily affected by buildings, mountains, or other obstructions.
FM broadcasts are transmitted at high frequencies and generally begin to fade at short distances from the station. FM signals are not as affected by buildings, mountains, or other obstructions, when compared to AM stations.
XM radio is transmitted through a satellite, rather than from a station, creating a larger reception area. However, if you are not located in a clear line of sight for the satellite, such as in a tunnel, in a parking garage, or surrounded by mountains, your XM signal may be poor.
There are multiple types of tints, some of which are metallic-based or consist of metallic material. The metallic particles help reflect the heat and light of the sun, keeping the interior of the vehicle cooler. However, the metallic tints can also have negative effects on the vehicle’s ability to pick up AM and FM signals. Since the back window is where the AM and FM antenna is located, this may cause the vehicle to have poor, if any, radio reception.