Final render. Dust and other atmospherics can really help control the eye.
Cranked the contrast of the render and started laying in photo elements. 'Soft Light' and 'Hard Light' layer types were new my best friends here.
Raw Arnold render with the new 'sun' light. Much easier out-of-the-box than setting up lights in older versions.
Alternate angle. This might be better if you're just doing to a concept for a vehicle modeler for an RTS or something.
My original model.
3D and photo-sourced concept for an 8x8 spider tank.