If the focus was indeed fixing major bugs in Android Auto, Google certainly had a lot of work on this front. The company never ships a changelog unless the new version includes a major new feature – in which case Google publishes a blog post to announce it. If you're a long-time Android Auto user, you're unlikely to be surprised, as this is part of Google's typical release strategy for the app.
The bigger problem is that Android Auto 9.7 comes without a changelog. Surprisingly, a beta build for this particular release never reached the web, so this time, we're getting the stable update directly, presumably as Google resolved an important bug in the app. The new version is 9.7, and it reached the production channel literally a few minutes ago. As such, manual downloading is the only option if you don't want to wait for the new version to show up on the Play Store. On the other hand, the Play Store release model means the new version ships to devices out there in waves, so some users will have to wait longer than others to receive Android Auto 9.7.