To make it easier for developers to test out apps designed for Android Auto, Google has released the Desktop Head Unit, or DHI, which effectively simulates the Android in-car experience on a computer. It’s a considerable step forward in car-based app testing, moving past the basic features of the simulator found inside the Android Auto SDK.
The DHI is installed on a computer, and convinces any USB-connected phone or laptop — running the Android Auto companion app — that it’s linked up to a car. The test app then operates exactly as it would when displayed on an in-car entertainment system.
Apps developed for Android Auto can be tested using the new Desktop Head Unit from Google
This lets developers give pre-release apps a complete test run in a realistic environment, without the need to have an Android Auto-equipped vehicle nearby. The only requirements are the DHI, and an Android phone running version 5.0 Lollipop or later.