If you use Android Auto with a cable this maybe of some use to go wireless. I've ordered a Pi Zero W off ebay for £10 and I'm going to give it a shot. I already have a an AAWireless dongle (which cost me £60; currently £70 on Amazon) but I'll be very interested to see how this DIY method compares:
https://www.reddit.com/r/AndroidAuto/comments/1f90agu/wireless_android_auto_dongle_for_your_car_using/?share_id=4fDbeKvxYGp_N1vcCQmQc