Pretty sure this is standard for all cars. As mentioned, phone calls are handled by the Hands Free Bluetooth profile, while everything else (music, S Voice, GPS turn by turn voice, etc.) are are handled over the Audio profile.
When the phone initiates anything over Hands Free, the car is designed to give it priority over everything else including the FM radio and other Aux inputs.
For all other Bluetooth audio, the car has to be set to Aux-Bluetooth for it to be played through car speakers, including GPS, text alerts, etc.
Hope this helps.
Posted via Android Central App