Ummm....you HAVE to create something in either 2-D or 3-D. There is no in-between. DarkBASIC can only produce either 3-D or 2-D, not 1-D or 4-D (although a time machine function would be rather cool..)
But about a car game, hmm.....my advice would be get the physics as close to the real thing as possible. Handling a car in real life is a lot different than handling a car in-game, so it's better for the gamer to be comfortable if the controls are a little sensitive.
About collision detection, I've never figured out the polygon collision, I've never gotten it to work, so what I do is 'break up' the level into little boxes or triangular shapes and use the corresponding collision-based shape for the collision. Quite helpful.
Sliding collision is a topic discussed in the following tutorials which I highly recommend reading before you attempt something too difficult, or even before posting another question. Here's the link:
TDK's Tutorials
That's my advice, hope it's useful! Happy coding!

Original image by BigAdd