I used the word 'grill' since forever and I intend to keep it that way 
As for the typo, nerves in my hands have been burned by almost 2 years of chemotherapy, basically killing any sensory feedback. At this point I'm happy I can still type things that even remotely resemble words known to humanity, so sorry, but you'll have to deal with my typos.
As for the modelling stuff:
Yeah, your mesh is way to fine to model it. (Unless you find a willing paymodder who will rip it off of something else found on high-poly model sites
) In your case a flat texture and optionally a normalmap does the trick.For the Ford's AO, as mentioned before, I'm using hybrid system. Some parts of the cab use a generic AO texture (generic, soft gradient, mapped manually in certain parts), as it gives a natural effect on highly visible surfaces. Example of that would be top of the cab, just underneath the protruding roof edge. This creates a nice, subtle effect, which isn't too much "in-your-face", but I'd say it's noticeable enough, especially if you compare the model with and without it. On the other hand, all of the smaller details, like all the borders between parts and doors etc. use vertex AO (basically solid, darker AO color), because they are so small, that a vertex color versus texture gradient don't make much of a visual difference. (and I find vertex painting less tedious) I'm not using normalmaps for the cab itself. I guess it would be a viable option, but at the same time, the cab doesn't really have all that much detail to justify the usage of custom normalmaps. I would go for one if the cab was rivetted, but it is not, so that's one thing I was able to skip. A lot of smaller accessories do use normalmaps for their shape though.
I've seen how the game itself incorrectly calls it "grill', so there's no way around that, of course. I mean, English is obviously not their first language so there's going to be some nuances here and there. 
And, 2 years of chemo? Holy shit, that's, like, more than 1 year! (Okay, that joke sounded funnier in my head. So hard to convey tone through text. 
Anyway, if I understand you correctly, there are smaller parts of an object that you'll purposely have as a darker shade than the rest of the main object? If that's so, then I was doing it correctly with my Legacy Sleeper and darkening smaller crevices to give a sort of "shadow" or depth to it. Well, that's a load off my mind, I wasn't sure if doing it that way was wrong. Or, give poor results.
