There are a few mistakes here, some areas needs a bit of blur, remember to use 0.3 feathering on your selections, you won't get jagged edges and there needs to be a bit of the left tyre too, but the main one is the rear fender, this is what it should more or less look like:
This looks awesome, my only real issue is the way it sits on the background, needs more shadow towards the front and right area of the car, you can see the sun clearly behind it. nice work anyway ^^