Google has been pretty closed when it comes to Android Auto. Only allowing some apps to actually support Android Auto, as well as fitting them all into a template so the experience is the same on every app in Android Auto. There was an interaction limit within Google Play Music on Android Auto. So you could only work in the UI with 6 taps at a time. This includes skipping music, browsing through a playlist and such. But with today's update, it appears that this has been removed at least for Google Play Music. This is likely the case with other music and media apps for Android Auto as well.
While the interaction limit is gone, it's not completely gone. What we are looking at here is the interaction limit is gone when in park. So if you are not in Park, then your interaction limit still exists. Some may be unaware, but even third-party head units can tell whether you are in park or not. For instance, with the Pioneer AVH-4100NEX won't allow you to plug in and use Android Auto if you are not in park. It's a bit frustrating, but it makes perfect sense. Why? Because you shouldn't be playing around with your phone when you're driving. Your eyes should be on the road, as always.
The update to Android Auto was pushed out today - as Google also launched Android Auto in 18 more countries today. The update is available over on the Google Play Store, and you should see the update available now. There's not much else new in this update, and it's a bit strange to see that this interaction limit is only for Google Play Music right now. We haven't seen it change for Spotify, Pocket Casts or other apps, so we'll have to wait and see if this change makes its way to other apps. It's strange because the change came about with an Android Auto update, not a Google Play Music update.
Either way, it's great to see Google continuing to work on Android Auto and make it better and better with each update.