Google understandably shuts down easy access to your phone when Android Auto is turned on, since you're supposed to be focused on the road. But what if you do need access to your phone while it's still paired with your car? It should be easy from now on: Google has quietly added swipe-to-unlock access to your phone while Android Auto is active. If you absolutely need to pull over and check a third-party messaging app (or have a passenger do it for you), you don't have to jump through hoops to get to your home screen.
The feature only just appears to be rolling out, so don't be surprised if it's unavailable for a while. Google hasn't formally announced the feature. The objective seems clear at this point, though: it's a balance between attempts to curb distracted driving and the convenience of accessing the phone directly if and when you really need it.