For S8 users follow robert_swiss instructions. The only differences are:
1) Set AVRCP from 1.4 to 1.3 instead of setting BPAP from 1.2 to 1.1. BPAP version option not available on S8 (well at least not on my S8).
2) Deny contacts in addition to messages.
For those who don't know how to get access to 'developer settings' , search in google for 'how to access developer options on galaxy s8'. Its very simple.
Works flawlessly. Not having messages is no big deal for me. Not having contacts is a bigger issue, but I use 'ok google' and ask the phone to dial a contact, rather than use the voice feature in the car.