The key success factor for AppRadio to work is the ability of the connected phone to output or cast the screen via HDMI, and a compatible adapter (either Slimport connector or the MHL adapter) is crucial to make this happen. This actually becomes the show stopper for many as not many phones can work with an aftermarket adapter. For instance, the One+ One and the Nexus 6.
With a series of posts on AppRadio I shared, some of my friends really got poisoned to do the same on their lovely car. Too bad, none of them are using Nexus phones, so I ought to further inject the poison making sure I have a solution for them! Glad that I do have something to offer!! *evil grin*
As wired solution is almost impossible for some phones, the alternative is to go on wireless. There are few matured wireless display technologies such as Miracast, WiDi and so on. The safest is to pick a technology that is natively supported on any Android phone, which is the Miracast.
A deep dive into Amazon and I found this...