ty all for the comments.

it ll be possible to have 4 players at the same time, so for now I assume we can have 4 vehicles in the level at the same time, i don't know if I ll include some traffic..

Right now im testing physic engines, ive already tried newton and it seems a really good engine, with nice features, but its an old plugin with some issues.
Since i have the pro edition, maybe the best for me and to have a good support here is working with the 3DGS physic engine (ODE). I think ll try the car project template just to have an idea of what can i achieve with ODE.

@Endgegner
the best way to create realistic textures in almost all kinda of models is using photos as references to texture it...

@dennis_fantasy
ty for your help, I ll contact u soon to check what u have for me..

@frazzle
I watched some tutorials to know how the best techniques to model cars, and i tried a bit in a previous model first, but i haven't finished it.

and ty Carloos for your help!