It wasnt necessarily a vignette. What I tried to use was lighting effects, and the spotlight made everything else a shadow.

Heres kind of a build up of everything I did..

This is the original picture, no touch up aside from flipping it right side up. Rig shots are taken upside-down to help keep the rig itself from showing up on the car. Its much easier to clone out the rig from the sky/background than it is to take it off the car...



Here I started to bring out my colors and stuff, as well as some sharpening and noise reduction. I do this before I clone the rig out cause Ive noticed once you start sharpening AFTER you clone, that path tends to show up more...



This is the last step I'm posting, I adjusted the levels here, then took out the rig and some dust spots here and there. You can go pretty much any direction from this point. I experimented with a few other ideas, you can also subtract the background and sub your own. And there you have it!