Got an s20+ and a 2014 too - calls worked OK, but the car needed to be coded to stream music (I have the base audio system with iDrive, others on here have said that this model year has a "combox"
You won't get album art, but you can skip tracks, change volume etc from the steering wheel.
If you're in East London, let me know and I'll pm the contact details of the guy who did my car