Not bad, not bad.
Only things that I can say that you should get rid of are the lines around your highlights. Like the the rectangle in the center of your side mirror. the line along your side trim thing.. or maybe lower the opacity. Also get ride of the lines on the hood or drop the opacity.
As for the coloring. look at the color of your hood and the rest of the car, it's lighter.
For your headlights you should have used the shape tool and changed the settings so that it leaves a path then you can scale it how you want and stroke it with a brush.
You should use a larger brush for the outline. (3-4pt is perfect)
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