Like the above say, the back wheel is a bit choppy; Try to avoid rendering cars if they are motion blurred or have smoke/gravel/crash effect, as this makes for very difficult rendering. I know, they're hard to find without those, but it makes it easier in the end.
I actually have this background currently on my desktop , nice cut seeing how the back wheel is covered in smoke
Indeed the cutting is nice, lill choppy here and there. But I don't like this image cause of the backwheel with the drift smoke around it, but that's just personall. Keep them coming.
I'm getting a user posted image, so I tried to right click-> view image, but it says Firefox can't find the server at psdcrate.
Accually i think the only problem is 2 things, Circles, and finding the right wallpaper or picture to render.