Maps for Chromecast

[ByrneDF]

I've got a Chromecast connected to the screen in my car that I'm using to show Google Maps. The only way I've been able to get it to work, however, is to mirror my phone screen, which requires the phone display to stay on, which kind of defeats the purpose.

What I want to know is if there are any navigation apps that support Chromecast (ideally one that will also let me cast music), or if there's any way to mirror the phone screen with the phone's display turned off.