I recently published a new Android app for streaming LibriVox recordings that supports Android Auto. It is called autoLibri. It is free (no ads, no subscriptions, and no up sells) and available in the play store now. If you have Android Auto in your vehicle, it makes it much safer to adjust the playback, than reaching for the phone. Give it a try and write a review. Let me know if you have questions and suggestions. It is a 1.0 app and features/fixes will be driven by usage.
You can see a preview video here: https://www.youtube.com/watch?v=ztWgJSzxd3I
Why another Android LibriVox app? My day job is developing apps for a vehicle manufacturer that is evaluating Android Auto app development.
David (long time listener, first time poster)