You might wanna reduce the polycount on those tubes and hemispheres. They look like bubbles ready to burst.
This is just my suggestion, but if you wanna really save on polys with Spheres, use GeoSpheres, it makes the sphere using triangles(1 tri/poly each) instead of squares(2 tris/polys each). Unless you're really going for a smooth sphere.
Using rough-shaped spheres rather than smooth ones make it look more mechanically natural.

The Turret looks really odd. Its shaped like a mushroom, its very oddly-shaped.
Why don't you make a base platform for the turret, then take out that mushroom stock lower half.

The barrel also would need a reduction in polycount. I suggest making it 8-sided or 6. Also reduce height segments to 1, or if you wanna change the shape of it a bit, the go set the appropriate segments.

The rocket launchers, they're not straight.
When I mean straight, I mean that they match the shape of the rocket-- a long unbent tube.
they putting them as unbent subobjects, and rotating them upwards rather than using the segments to form the diagonally-upward facing nature of them.

The Chassis look very bland, unless you can find good textures to make it look interesting.

Originally Posted by: Zatsupachi