2) Click Devices, Drag your car profile to the top

https://play.google.com/store/apps/details?id=org.myklos.btautoconnect

That solved it for me. 

You could also do it with AutoWear + Tasker. 

Essentially once the phone connects to your car's BT, it will create a floating Icon on the watch, wait 2 seconds, and then turn off your watche's BT. Tapping the icon will send an action to turn the BT back on. This is necessary since if BT is turned off on the watch, there's no more communication with the phone.

Once you set this up in AutoWear you can use BTON in tasker.

Bottom profile:

EXIT TASK: This hides the icon when disconnecting from the car BT.