Yup, I was surprised by this too. This thread has some discussion (but some points are a few years old):
https://xdaforums.com/t/how-to-prevent-android-auto-from-establishing-bluetooth-connection.4478463/
Some hilighted comments are:
- There may be a setting to disable Bluetooth in Android Auto (car side) settings (?) but maybe not on newer Android versions like we have.
- If you remove phone permissions from the Android Auto app on your phone it may not then enable bluetooth. Also take out SMS, etc. that you don’t want it to have.
- Last post was from a few days back, this user fully disabled bluetooth on their phone. Not sure if you use it for calls, etc. though.
Anyway, it would take a bit broader digging and testing, I would hope it is still possible one way or another. Keep us updated (or maybe someone else will point us both in the right direction 