Google have announced the release of a new emulator tool for developers who want to target Android Auto.
The DHU enables your workstation to act as an Android Auto head unit that emulates the in-car experience for testing purposes. Once you’ve installed the DHU, you can test your Android Auto apps by connecting your phone and workstation via USB.
Your phone will behave as if it’s connected to a car. Your app is displayed on the workstation, the same as it’s displayed on a car.
Developers can now test development versions of apps in a production-like environment, without having to work from your car.
You’ll still need to connect your phone, but this will give a much better sense of what drivers will get from the app  all without having to actually get behind the wheel for testing.
With the release of the DHU, the previous simulators are deprecated, but will be supported for a short period prior to being officially removed.
Check out the developer guide for more info.
