If I wanted to use these models in CGI I would need a lot more detail than what I can model.
Not really. That's just too much work and there are other techniques for that, for example displacement. Check out this test render I did a while back:

That whole model actually has only about 60 000 polygons so, something on par with your models. None of the small details, like the cogs, the bolts, blast marks etc have been done with geometry, as you can see with the wireframe:

Instead, all that detail was done in ZBrush and the normal maps and displacement maps were applied to a low-poly mesh with a level 1 subdivision applied. Zbrush version has probably more than 30 million polygons when all parts are added up.
Now, games don't support subdivision and displacement because it slows down rendering a lot, but they do support bump-mapping which is like a poor man's version if displacement. And for games, where a lot of things are happening on screen, that's usually good enough.
Of course, if you actually want to make a machinima of sorts with your models, then I understand where you're coming from. BUT, for a game model to look good, you really do want to UV map it and texture it. You also want to set up your tangents right, because otherwise you'll get weird lighting artifacts in Sins.
@Thoumsin, yeah, maybe that trick with the shader would help - personally I've never used it like that. I am still not convinced that Sins engine won't chug down to a crawl when too many polys are on screen. My Volumetric Explosions mod uses a lot of tiny low-poly chunks when ships blow up, which CAN slow down the game if I explode like a whole fleet at once.
And those are only 20-50 polygons each. So I'm thinking, if Softimage slows down CGI rendering with 1 million polygons on screen, chances are IskatuMesk just has a really good computer if he experiences no slowdowns with 20 million polygons on screen in a game (or Sins engine is really awesome). Actually, I have a 64-bit system and ZBrush sometimes runs out of memory if I get near that polygon count, never mind a game. So performance is definitely a big issue with that kind of numbers.