How to make a model'd car drivable just like a real car. Please help.

First off, I am definitely not a noob at lua. I just have never tried a car script before.

I was wondering if someone out there could help me make my friends car, pre-model'd drivable when the player press's USE on the door area. If you could help me out then I owe you a major thanks. 

Please post if you get a chance -thanks!

What exactly is a “pre-model’d” ?

Do you mean your friend made a car model with all of the required bones and animations, or is it just a plain static model?

Bones and animations
-Sorry about not being clear

Your not the OP

I am his friend. - The one with the model

To add it to the spawn menu I know you will need to use list.Set() as seen here :
http://luabin.foszor.com/code/lua/autorun/base_vehicles.lua

As for making your own vehicle script you should take a look at garrysmod/scripts/vehicles/ for valid examples.