I used this on my VW Passat with a Pioneer 4000NEX head unit. The app you're referring to is AppRadio Unchained. As far as I'm aware, there's not anything comparable for Android Auto quite yet as the API isn't public. We'll see if anything happens with it.Looks like people are using some kind of home brew of appradio to mirror all content on there phone onto their pioneer head units...
Home Brew of appradio let you use anything you have on your phone on the main screen..
Is there anything in development or out now that would do the same to our screen?
For reference, here's my 4000NEX with my old phone, running Unchained.