When I connect my S4 to my car's Bluetooth, it starts playing music (UNWANTED). How can I stop this?

[AC Question]

When I connect my S4 to my car's bluetooth, it starts playing music (UNWANTED)

How can I disable this automatic music playing? There is no run app, its just music out of the twilight zone coming from the phone.

I want to use my car's bluetooth audio to listen to driving directions. This works (usually), but I also here random music on my phone.