I spent the whole day googling and trying to figure out why Android Auto does not work anymore with my new phone, when it has been working for two years with my previous phone. I hope this post gets found via Google by other frustrated users.
Step 1: Phone Settings > System > About Phone > Software Information > Tap 7 times on Build Number to enable Developer Mode
Step 2: Phone Settings > Developer Options > USB Debugging On
Step 3: Phone Settings > Developer Options > Default USB Configuration > Set to USB Tethering
Connect your Phone to your car via USB and Android Auto should start hopefully!
Just done this on mine as, since I had the new firmware and maps my AA has been playin up on connection and dropping connection as well, 2017 Rio first edition. and S10. but was working prior to latest update.