That's looking really good!
A little constructive criticism: you may want to consider making the rear spoiler a little thicker as it looks like it's kinda wavy. If you make it another layer of plastic thicker and sand/file it down to a "sharper" edge, it'll hold its shape better.
Yea, Im gonna add putty behind it and build it up, thats not the final design. Thats just the base structure. But, it gives you an idea of the look Im going for.