One of the biggest challenges to creating good apps for Android Auto has been actually testing the experience. Many independent developers can't afford to purchase brand new cars with Auto built-in, and aftermarket head units won't fit in most recently manufactured cars without heavy modification, and most of those units aren't very good anyway. When the Auto SDK came out, it included simulators that could be used for basic testing of just the messaging and media browser interfaces, but even these weren't good substitutes for the real thing. Today, Google released the Android Auto Desktop Head Unit, a functioning implementation of the Android Auto platform that runs right on a desktop or laptop.