clay renderings are so dated and look bad on high detail stuff because it blurs everything and you can't see shit. Check out this tutorial to setup something nicer: http://www.artemstudios.com/08Portfolio/Tutorial/MaterialRenderingTut.htm
its still to similar to the digital tutors tut model, add in some tire tracks and better exhausts, if you look at the reference you get with that tut the exhausts are much bigger. also there is no suspension ...