Non-ideal but extremely effective solutions:
a) In cars equipped with wired CarPlay/Android interfaces we've found that the use of "Wireless CarPlay Adapters" resolve the problem completely.
My brother uses a cheap ($43) Yshnples Wireless Carplay Adapter he purchased on Amazon specifically to cure this problem. Potential issues to look out for include an inability to easily between the phones of multiple drivers. They can also be slow to connect but they work.
* CHECK VEHICE COMPATIBILITY!
My son is waiting on a OTTOCAST U2-AIR Pro Wireless CarPlay Adapter for iPhone ($129) for his Jetta.
Advantage of this adapter is that it's easier to switch between drivers and is virtually lag-less. This one is NOT BMW compatible, so again * CHECK VEHICLE COMPATIBILITY!
If drivers are Apple & Android you'll need a device that supports both like the OTTOCAST CarPlay Android Auto Adapter U2-X Pro - 2 in 1 CarPlay Dongle or similar.
b) For cars equipped with aftermarket add-on CarPlay modules. (Like my MINI Clubman)
Check your device settings (through the device or the "Home" icon in CarPlay)
Go through your devices settings/Setup options for Audio configuration and look for your Mic settings.
Once found you'll want to look for an option called Auto Setup, AEC Auto Setup or similar and select it.
Note: You want to make sure the car is off and that you remain completely silent during the process.
Once started you should hear a repeating tone for about a minute.
When it's done you'll note the microphone settings have all been automatically adjusted by your device.
Back out of the menu and return to CarPlay to place a call. The problem should be resolved.
If your add-on module does not include this option it should still provide a USB interface for CarPlay, through which the devices listed in A, above should work.
c) Other CarPlay head Units
In various threads we've found references to the ability to completely disable CarPlay through head unit options.
Apparently noise cancellation settings are obtained during the very first connection and at no other time.
For this reason it is recommend to completely disable CarPlay if you can.
Remove your CarPlay connect from all phones that currently use it.
Re-enable CarPlay and connect. It's HIGHLY recommended your iPhone be on the latest version of iOS!
For those with head units that include the option to completely disable CarPlay this appears to have a fairly high level of success, but it's not something we've been able to test.
For us the solution was A and B.
I know how ridiculously annoying and widespread this problem is and I really, really hope this helps you resolve it once and for all.
Good luck and best wishes.
