I made a vehicle in automation. I want to be able to use all the engines, trans, brakes and all that good stuff that all the vanilla cars use and I have collected in my parts list. Is it possible? I'm guessing if it is its going to be editing files. Any help would be great.
It isn't possible. You have to edit in blender and mod the car. If you want to try, watch videos of Fillman86. He does this a lot, and (i think) has guides.