Google announced Material You as the successor design language to the already aging Material Design. Since then, the company has been implementing it across its products and services. However, there are still Google products that haven't integrated it, including Android Auto. That seems to be changing as the latest Android Auto 13.4 update integrates Material You color accents throughout the system.
Material You introduced a series of guidelines to maintain cohesion and familiarity between all the services that implement it. One of those guidelines is the integration of dynamic color accents. That is, UI elements highlighted by color accents extracted from the dominant colors set on your phone. This is similar to how some music apps adjust the playback UI's colors to match the album art.
Now, Google is integrating Material You color accents into the latest Android Auto 13.4 update. As reported by 9to5Google, they're present across multiple elements throughout the OS. This includes buttons, toggles, menu backgrounds, card backgrounds, notifications, and the notification center. For the feature to function correctly, you must enable the option that allows Android Auto to match your phone's wallpaper.
While it's a step forward in terms of UI, the initial implementation is far from perfect. It is possible for the accent colors in Android Auto to not synchronize with your phone when you change them. Sometimes you might even need to force close the Android Auto app for the colors to change.
Another issue, which might not actually have a fix, is that accent colors aren't applied to app UIs. This is pretty normal, as each developer has full control over how their product looks. The move seems like an attempt to modernize and make Android Auto's UI more attractive.
However, there is still a lot of work ahead until Google implements the idea correctly. Google has also improved the functionality of its "smart vehicle" platform by integrating Gemini capabilities.