https://www.amazon.com/iSimple-Hands-Free-Calling-Streaming-Smartphones/dp/B00FRU5UNA
I put one of these in one of my older cars that has a factory navigation touch screen thing I didn't want to get rid of(but no bluetooth), and for $75 I honestly have no complaints. Android Auto and voice commands are now quite useful.
I've been replacing the volume controls on Becker 1492's and the like for awhile now and plan to put one in my E320 here shortly.