The only difference with wheeled and non-wheeled cars is this...
Wheel models aren't needed at all, obviously... they aren't loaded or called from the parameters.txt at the top part that has all the directory info.
In the wheels section, the wheels are disabled with a negative one "-1" in the model number section of that.
The Mystery is a good example...
MODEL 0 "cars\Q\body.prm"
MODEL 1 "NONE"
MODEL 2 "NONE"
MODEL 3 "NONE"
MODEL 4 "NONE"
MODEL 5 "NONE"
MODEL 6 "NONE"
Notice how there is only one model in the models list. The ModelNum variable takes that number and looks at the corresponding models for a file name to load for each object. Since there is only a body on the Mystery, that is all that is needed.
Since obviously this car was made for no wheels in mind, it has ModelNum set to -1 for the objects that don't have corresponding prm models for. If, for example, you left the wheels as ModelNum 1 and 2, and the directory was set to none, the car would crash as it was done loading with the track. The car doesn't crash in the menu, but a really odd and funny behavior occurs... all the wheel models are replaced with the only model, the body. So you have a body with 4 outer bodies in the positioning of the wheels. Obviously unwanted behavior!
This is what needs to be set to negative one...
WHEEL 0 { ; Start Wheel
ModelNum -1
You see that -1? That means that the game doesn't try to look for a model for the wheels, they are thus, nonexistent. If the wheel models were set to their defaults of 1 and 2, it'd look at the directory "NONE" and then give you a heartwarming crash. -1, means that it ignores the model numbers and directories, it's like a NUL, so to speak.
WHEEL 0 through WHEEL 3 will all need to have their ModelNum set to -1. This rule applies for all models, that's how cars have spinners and stuff disabled with a -1. You could actually disable the body too, but that's near pointless.
As for Urne's response to question #1, he sees things that way because he is a track maker lol, ase2prm wasn't really adequate for me, the vertex normals are horrible regardless of what smoothing I use. And I couldn't get transparency to work
The way I get stuff from 3ds to Re-Volt, I export it as a 3ds file, import into ZMod and work from there, exporting the prm in ZMod.