"Teh red wuns may go fasta." Now that we got that out of the way, onto my take.
Good, subtle checker pattern. That said, I'd much rather see this sort of subtle effect on some nice, elegant Eldar grav tank than some ork burna. After all, the Orks aren't subtle. The attention to the bluing exhaust is another good touch. The base is just plain cool. How did you make that asphalt? If I were to guess, you probably took some gravel basing material and mixed it in with epoxy putty, smoothing it out into sheets. But it works really well, and is something I'd like to try.
Two small criticisms, but they are easy fixes. First, those orks have such deep brows and sunken features, I would have liked more of a shade around the eye sockets. It would make the red pop out even stronger. Secondly, I would have liked more stikkas, dekalz, and insikniaz on that thing: glyphs, advertizers (I take it it's a racer), and kustomization. The basic paint scheme is well done, but a bit monotonous. And while I would't drown this fine model in decals and glyphs, three to five would make the model truly awe inspiring.
This goes for your crew as well. This is where your knowledge of the lore and imagination can work well. Blue is the traditional color of the Deathskull tribe: master lootaz, who traditionally paint their faces blue.