Lovely piece, great execution. I only have a few crits. The texture could use a bit more details here and there (where is the oil and mud?). Fortunately there's plenty of rust...
Render looks neat
, but i would definitly desaturate the blue light, and let it cast shadows. it will probably fix the odd blue lighting you have atm (best visible on the last image you posted).
Overall definitly a portfolio piece. Nice job.
Now show us the textures
