Seems that Bluetooth Audio (music & notifications) and Hands-free Audio (calls & message reading) are two separate and different things, and one can definitely exist without the other, good news for us, those who don’t use the phone as a media device.
Instructions to disable Bluetooth audio via car’s speakers:
1. Pair your phone with Sync via Bluetooth
2. Select your phone, from the top left corner
3. Now press „Info” tab
4. And disable „Bluetooth Audio” by pressing once on it!
And that’s all! Now you’ll be able to listen to music via AM/FM/USB/External and all sounds (key clicks, lock screen, app sounds, etc) and notifications will be routed to your phone’s default speakers!
Call answering and voice commands will still be available via the steering wheel buttons, so the hands-free operation is still in place, with call’s ringtones and audio being routed to your car’s speakers, being able to select the volume via the car’s commands!
Remember! By using this method, you’ll be unable to play music from your phone to the car’s speakers, if you select „Bluetooth” from Sync menu, a message will be displayed saying that „No Bluetooth audio devices found / add one”.