A bluetooth FM kit is very convenient because it connects a smartphone to a non-bluetooth car radio. It’s a solution to listen to Deezer or Spotify music on your car radio or to take hands-free calls. An FM transmitter connects to the car radio either by jack or by FM signal. The connection on the auxiliary jack of the car radio (take AUX-IN) is the most reliable solution for sound quality and to avoid sizzling.
This is an interesting article to read: Steps to installing Google Maps