Some would say that Android Auto is a godsend but it isn't without its inconveniences. For one, a majority of supported vehicles and head units out there currently require the supported device to be tethered to the head unit through a physical cable to get things working. Of course, there are exceptions, but for most, plugging in their phone to their existing head unit is just a way of life. But this could all change, as an ambitious developer is working on a way to force a wireless connection with current Android Auto head units that don't natively support the feature.
The project is currently being worked on by developer Emil Borconi. A wireless connection is made possible by utilizing another device, in this instance a £14.99 Android TV stick, and using this as a Wi-Fi antenna for the vehicle. The companion app will then "transform any Android-powered device into a Wi-Fi receiver for your Android Auto compatible Car/Headunit". This will allow the device to connect wirelessly to the head unit and utilize Android Auto.
Of course, this isn't the simplest means of getting wireless support for your vehicle but it does probably beat shelling out hundreds of dollars on a new head unit. For now, this is just a concept, but if you are interested in how it turns out, you'll want to check out the link down below.
Source: XDA Developers