I've got a strange wire (strange to me at least) attached to the filler to my tank. You can see it in this picture with the nut on it (black wire). It can't be a ground since that is plastic. Is it some kind of anti-static wire? it runs back into the harness below the tail light on the pass side somewhere.

There's clearly a mount for a bolt there. Just can't make sense of why it's there.

 

Yes it is a anti-static wire. It goes up to the right to a ground post behind the tail lights. I cut mine to remove the filler neck and then put a butt splice back in when I put it all back together