I know that not everyone cares for carplay, however I do, and I have grown accustomed to having it in all the vehicles I drive. Since I recently picked up my 06 Z4 and it had NAV, I preferred to leverage as much of the built in system as possible without having to put in an aftermarket radio and all that. I saw several options (the android screen would be my next choice if this doesn't pan out over time).
I will be revising this as I go as more of a DIY since, NAVTool does not appear to have any valid documentation on how this actually get's installed, and has never responded using their chat feature or email. I was lucky that whoever answers their text line, gave me enough information to at least make some sense of it.
Here is what I purchased from NavTool:
https://www.navtool.com/bmw-z4-2003-...e-carplay.aspx
I will add that I have a GromBT3, with the charge cable and 3.5mm adapter and I do use an rca to 3.5mm jack to allow the audio from the carplay to come through to the factory head unit. You could leverage the built in aux cable if you have it, I preferred to keep things as clean as I could, when I am finished, there will be a single connection for my iphone for carplay.
I have got it working, even without any real form of instructions on how this works at all. Still waiting for the rear/front cameras to arrive, and I'll be writing up once I get everything in over the next week or so. At least in testing before putting away everything and finding suitable power and ground (I used a 12v power supply just to get it going) to make sure it actually worked.
I have ordered the momentary switch, front and rear cameras, and positaps for power to make things easier on myself. I have also ordered a panel mountable USB extension so I can just plug in the iphone cable and be on my way. I also found you would need about a 1.5' 3.5mm extension cable for infrared eye for the remote they provide. If you are going to leverage your aux connector, you'll need a stereo male RCA to 3.5mm male that you'll need to route from the carplay harness to the aux in. I also ordered RCA male to male coupler, to connect the video output of the carplay box to the video 3 input of the BMW18 (the add on video interface)
Outside of this, zip ties, electrical tape, google, and cable sheers would be handy. It would also be handy if NAVtool supplied current instructions, the ones the provide...well they are not current at all.