Incorrect information regarding first car to support this option.
BMW cars with iDrive 5.0 already support Wireless Apple Car Play. All 2 series, 3 series, 4 series, M3, M4 cars built since July 2016 have 'Wireless Apple Car Play'.
My M4 (built Aug 2016) has it... and it does not require any cable, all works via Bluetooth.
Here is another article from Mac Rumors stating the same.
https://www.macrumors.com/2016/08/01/bmw-2-series-carplay/
Wish my 2017 i3 with 5.0 iDrive had CarPlay
Wireless CarPlay is working in your M4 over Bluetooth? Interesting. I thought it needed wifi for that.