Modeling/Exporting/Importing workflow?

Does anyone know of a tutorial, set of tutorials or any other source that basically lays the entire modding process out for vehicle models? 

I'm a 3dsMax user and would like to start creating low poly vehicles for gta4. There are so many great looking vehicle mods out there, but a good chunk of them are well above 100k polys (I've even seen a few that are over 500k), a lot with unnecessary resolution, and just create more problems in-game than they're worth. Some of these car packs that are available, which are great in theory, just aren't a viable way to replace the cars in game as you eventually lose all your textures. I'm running the game on an i7 system, ssd, gtx 670 with 4gb of vram and 16 gb of system ram, have tried countless commandline.txt configurations, the large address flag, etc. The game just does not handle vehicles above a certain poly count, especially when you want to replace more than a few vehicles.

Anyway, I come from an animation and illustration background and have basically no experience creating content for games, other than texturing. I've gathered that I will likely need to utilize zmodeler for converting files and/or will have to use the GIMS scripts for Max, but that's about it. I don't know the particulars for setting up UV coordinates, materials or collision objects specifically for the rage engine. I intended to do some reverse engineering to hopefully figure some things out on my own, but if anyone has any advice before I dive in, It would be appreciated.

Thanks.