Here is the first draft of the finished model.
Looking at this image while doing other work on the computer proved useful because, after the initial satisfaction, I started finding faults with the look of the model that I probably would not have noticed had I been still working on the model in Max.
I decided to slightly increase the height of the dome, and to taper it in at the top a little bit more.
I increased the size of the 8 nozzles by about 5%.
I decided that the wheels could do with being bigger and increased the size by 5%, and increased the size of the mud guards by the same amount.
I also noticed that the mud guards were too close to the wheels so I raised the mud guards to increase the clearance.
Importantly, I also decided to change the angle of the wheel arms from -20 to -25, which made the body a bit more compact and also increased the clearance of the body from the ground.
The final decision was that the wheel hubs would be implied by a combination of diffuse texture and normal map, has opposed to modelling the detail in. While it would not be has convincing up really close, in C&C3 you can mostly never get close enough for it matter.
On to the 'really-not-that-exciting' task of unwrapping.