In May of last year, I traded in my 2011 X5 (E70) for a 2017 X5 (F15) and therefore I had to redo some customizations. One of them includes installing some hardwiring for a radar detector (was using an Escort Redline, but now a Uniden R3).
This time I was going to attempt a "mirror tap" install instead of the usual "leach power from the cig lighter and run a really long cable under the dash and under the A-pillar".
I tried two different mirror taps ($20-$30 each!) and neither had long enough taps, so last night I built my own for about $1.00 (because I already had most items on-hand) and about an hour of my time.
This instructable covers the actual mirror tap install process:
https://www.instructables.com/Radar-...n-for-BMW-X5-/
Sorry I didn't take photos of the cable-making process. It was getting dark outside and I just wanted to get it done. I added the step and a wiring diagram though!