Do it!
Spring doesn't like shading very much and the more you do, the better it'll look. Your barrels are not preshaded (and should probably look smoother.) Those triangular prisms, coming off the air pads' sides need to have shadows under them. The sides of your model need to be darkened. Guess on this by looking at how straight it is with the y facing. If it's flat, then it's going to be receiving more light. If it's sideways, it'll receive less light.
If the main barrels are static, do some drop shadows for them. The shadows should be pretty weak because they may throw shadows on a map with powerful lighting.
Also, underneath the main barrels, that triangular intrusion should be darkened on it's sides and edges. Most of the time, an enclosed space like that will not receive much lighting.
Reflections can also be textured. My tank's skirts have a hint of grass green which could either be wear and dirt or a reflection of it's surroundings.
Your treads could use some work, as well. Please don't render things with shadows. It gives us a false look at what your texture may have on it.
Your radar needs transparency and a wire mesh look or a new texture or design.
The white on the front is... not supposed to be there. It'd be nice to have the paint peel off to reveal metal or something, rather than such a bright color.
Hope I was helpful.
