So I was trying to figure out how to get my wife's Garmin GPS cig lighter adapter hidden and run cleanly to the center of the dash near the windshield for a nice mount. After some thought here's what I did and it worked great.
First off, I'm using the BMW flashlight 12v adapter for a direct plug without splicing since I have to go 5v on the GPS and 12v on the plug, so the actual plug needs to stay in-tact. So that part is needed... it's a few bucks.
I removed the passenger front top dash cover and removed the 2.5" speaker. I ran a probe (coat hanger) down the hole for the 2.5" speaker and into the glove box. I crimped the usb end of the Nav unit to the probe and pulled it back through the speaker hole. From there I pulled it to the length I needed and left the small remaining amount in the glove box. I re-installed the speaker into the opening (never unplugged the speaker) and put the grill back on after routing the cable to the back between the windshield and dash. Can't see any of it. The grill cover went back on and I had successfully routed the cable 'through the dash' with ease (I didn't want to remove all of the center console mess if I didn't have to.)
So from there I can attach and detach the little nav unit as needed and plug into the 5v usb plug waiting near the windshield. If I want I can tuck it in so it can't be seen.
Took about 15 minutes and didn't require a single splice OR the use of any of my 6 12v outlets

Besides, have you ever tried to USE that flashlight? It puts out about 2 candlepower.
The aux power adapter can be found
HERE
Just thought I'd share in case someone wanted to run power for an aftermarket GPS cleanly without any muss or cables showing!
Adam