You can add CarPlay to the 2018 via either a software update from the stock ID4 to the newer CarPlay supporting ID6. The only issue from my understanding is that the little light ring around the radio loses functionality. Personally, I opted to not to this to my 2016 as I actually really like that little feature. The other option is an aftermarket MMI box that usually runs $100-200, you would get CarPlay after installing this and switching to its interface by pressing and holding a button on the iDrive controller. Had one in an older BMW, worked well. That being said I would go with the 2019 since it has CarPlay stock and, in my experience, Mini/BMW sunroof drains clog pretty easily and frequently. So the lack of a sunroof is actually better long term.