First off. I have zero experience with aftermarket electronic accessories. I just bought a Garmin Nuvi GPS and I did not like the idea of using the cigarette lighter so I decided to hardwire it to my BMW X3 2004.

I found a fuse to connect it to but where do I connect the ground wire? I was told to look for a black bolt or screw. I do not see it anywhere. Anyone know where it is located? What does it exactly look like?