Went for a slightly unorthodox approach for how the car looks, at least at the rear, here's the high res (2048X2048) skin and preview. Based on Gumball 3000, decals are sponsors of the event.
I've only ever done 3 other skins in the past; 1 as a tester, and 2 private, still a newbie so thanks for the advice.
The only time I have used filters on this skin above is the rear design, which I presume is why you said it
Here's a render done by a friend Drew of my previous skin which is private. I am happy with it but would change the front if I could (be bothered). The headlights were screwed on the render, they are just red.
I will make a few more skins, picking up some pointers and techniques while messing about on these, but I like to be different in styling so I might have a love it or hate it way of doing things.
EDIT: attached is a work in progress render of my skin by Drew. (Drew is ace!)