I agree with everything that's been said but don't lose sight of what it is you want to achive as that is your main motivation - it sounds like a great little game you have "in your head".
I'd recommend you try to break down your goal into smaller, more achievable objectives, for example:
Objective 1: Load in .x model of truck and manipulate with user input
Objective 2: fine tune your input routine to get something that resembles vehicle control
Objective 3: Get your vehicle "driving" on a matrix (see the Tank Demo for how to habdle the roll, yaw over the hills)..
and so on...then you get to build up the skills you'll need so you can put it all together into your game.
Good luck!
"My ignorance amuses me..."