Have you got a chevy template yet? I have changed my career car out now i just like a template so i can make me a nice one.I'm not entirely confident in the "Mod Maker" EXE's at this time. I began to see problems as I made more and more modifications. That is why I plan to release an updated 2016 carset as a full on .rab file that you will replace over your existing cupcars2016.rab or cupcars2016_4k.rab.
Once I have more understanding of how the utility can work, maybe I'll release mods with it, but for now I think I plan to steer clear.