This only works if you have an empty/blank slot in the row of buttons below the center vent.
Garmin Nuvi AMPS Adapter Mount - $6.00 (http://www.gpscity.com/garmin-nuvi-amps-adapter-mount.html)
2.5" 10-24 machine screw
some wire and a couple of ring terminals for 1/4" posts
female cigarette lighter plug - $4.00 (http://www.autotoys.com/x/catalog/CIGARETTE_LIGHTER_PLUG_LEADS_FEMALE_p_5460.html - radioshack has it too, but I can't find it right now)
First off, there are at least two ways to do this. Originally, I tried to mount the ball to the blank without pulling out the vent and reinforcing behind the blank. Unfortunately, while this would have been a much easier solution, the mount was unstable and wobbled a lot. Therefore, you can see the steps I took below to reinforce the mount (with the wood block/clamp mechanism I built).
1) Locate a blank insert where you want to mount the GPS. In my case, I have two heated seat buttons and a defrost button. This left one blank slot leftover for the GPS mounting ball.
2) Pop out the blank and pull out the center vent assembly.
Follow the steps under center vent in this thread: http://forums.vwvortex.com/zerothread?id=1960541
3) Remove the mounting ball and bolt from the garmin amps mount plate. Drill a hole of the appropriate size through your blank panel. Replace the machine screw that came with the garmin amps mount plate with the 2.5" long screw.
4) Cut out a piece of wood (I used 1/2" mdf) in the shape of a trapezoid, as pictured. Drill a hole through the wood for the bolt. This wood serves as a "clamp." As you tighten the screw, it pushes the retaining clips for the blank panel outward and holds it in place.
5) Notch out a hole in the blank panel for the GPS wiring (if desired)
6) If desired, route your GPS wiring up behind the radio and out the hole you notched in step 5.
7) Pop the blank back into the vent assembly. Place the wood-trapezoid block behind the blank panel and tighten until the mounting ball and blank plate are tight in the vent assembly.
8) Replace the vent assembly
9) Hard-wire the female cigarette lighter to the 75x terminals on the fused box. This turns on the power to the GPS when the car turns on. Follow the directions in this thread to access the switched 12V terminals.
10) Enjoy the final product!
Modified by tadr_94jetta at 4:30 AM 9-17-2009