The Bg on this is rather awkward IMO. Try to stay away from creating your background for solid shapes only. They are great to use, but GFX is about moderation. Solid shapes are great for adding style and your own flair to the BG(background), however use EVERYTHING in moderation.
Also with the scan lines, They use to be VERY popular, however now they are kind of out of style, however that is not to say you shouldn't use them, but don't cover the whole sig with them. Maybe only a part or two.

The blending on this is okay, though it could use some more on the right side. You did make a smart move though, trying to smudge over the Blown out white part of the car. That was very smart, next time try to make it look a bit more natural by moving the smudging into the BG a bit as well.

The coloring on this looks pretty nice. SO you did a very good job on that.
The text is okay, but you want to remember to use a default font, and to keep it small. It's supposed to blend into the sig, not attract that much attention.

I recommend you read this guide to text:
Darkmethod's Guide to Text

Also i think you should read a couple of tutorials they will help you a lot.
I strongly recommend my tutorials (:P), daemon's and ilovecoheeds, but they are all good so go check 'em out.