How to stop music apps from playing when connected via Bluetooth to my car/headset/receiver?

We recently bought a used Toyota Prius that has Bluetooth installed with the JBL audio system. Whenever my phone (stock Nexus 4 running 4.4.4) connects to it, the car sends a "play" command that automatically starts the most recently used music app (Google Play Music, Pandora, etc.). It doesn't matter if no music app was open on the phone, the command opens it up and it starts playing no matter what, and there's no way on the car to stop it from sending the command, as mentioned here . Is there a way to stop this from happening?