At Google I/O today, Google announced the new update that is coming soon. Android Auto is going to be available to a lot more users starting this year. You’re not going to need a car or third party head unit with Android Auto.
A new update is coming to the Android Auto app later this year that will enable the full Android Auto experience right on the smartphone itself, without needing to be plugged into a compatible car. The main idea is that anyone could snap the phone into a dash mounted cradle of some sort. The App will work like the in dash Android auto experience, the on phone UI is simplified and the voice-centric keeping distraction to a minimum.
To hear music and navigation you can use Bluetooth streaming or a 3.5 mm aux in jack with your car stereo. You can use inbuilt car speaker or a portable Bluetooth speaker, that’s the freedom of using your own phone.