This is a nicely done!
Under the car should see the background, now there is only two different gray, why? :O
The right tire is also cut..
The rear lights darken is not authentic (as well as your quick Subaru).
When you darken the lights, or windows, use the "shadows, mid tones and light areas." That way, you darken the lights a lot, but you get bright reflections.
(This menu can be found in PaintShopPro, but should also be found in Photoshop. I dont know then if you use the gimp, is there that kind of menu.)
Keep it up!
