How can I use Android Auto without having to open the app on my mobile device?

To use Android Auto without having to bring the app to the foreground on a mobile device, follow these steps on your device:

Go to Settings > Apps > LiSTNR > Appear on top/Always on top > Enable

Once this is done, then launch the app once on the mobile device. The next time you want to launch the app directly from your car interface, you will able to do so.