Save my ears! Apple Music starts in the car STILL

Depends on the head unit in your car. Some will have the option to change the input source to another such as FM instead of Bluetooth Audio so the car does not play sound from your phone when started. Other newer models have the ability to pause Bluetooth Audio in the head unit.

The phone will play Apple Music when it is connected, so it will be available when you choose to play Bluetooth Audio. If it did not do this, then you would need to start playing the Music on your device when you chose Bluetooth Audio on your head unit and that would defeat the purpose of having a Hands-Free device.

You can create a shortcut that will automatically pause Apple Music when it connects to your car. This will require you to start playing the music on your device when you do want to listen to Apple Music. Follow the steps here to create your very own Shortcut:

• Open Shortcuts app
• Tap Automation at the bottom of the screen
• Tap "Create Personal Automation"
• Tap "Bluetooth"
• Tap "Choose" under Device and select your car
• Tap "Done"
• Tap "Next"
• Tap "Add Action"
• Tap "Media"
• Scroll down to the Playback section and tap "Play/Pause"
• Tap "Play/Pause" on the top of this screen and choose "Pause"
• Tap "Next"
• Tap "Done"

If you decide you don't want this automation after creating it, you can simply delete it from the Shortcuts app.

iOS 17 added an extra step to prevent shortcuts from running automatically, so you may need to turn off the "Ask Before Running" option on the shortcut as explained in the user guide:

Some personal automations can run without asking you for confirmation when they’re triggered.

1. In the Shortcuts app  on your iOS or iPadOS device, tap Automation .
2. Tap the automation you want to run automatically.
3. Turn off Ask Before Running, then tap Don’t Ask to confirm your choice.
4. Tap Done.
5. The automation will not notify you when it’s triggered.