If you have no experience at all, you might want to start with something simple like Gingerkid Jack suggested.
However, if you do have some experience and really want to make a racing game, I would start by making a really simple world model to load and making a player object to drive on it. The player could be a cube for now, it doesn't matter. Once you get the player controls down, you can change the player model into an actual car. You can also then start to make your first track.
So I'd start by working your controls out on a test track before you start making the final models. Worry about the game first, then worry about the models.
Also, racing games can be complicated, especially when it comes to detecting when a lap has been finished, what position you are in, etc... You could just make a driving game where you just drive around, in which case you wouldn't need to worry about these things. Or, if you want to be a little more complex, you could make a race against the clock where you have to get from start to finish. It's up to you, but try to stick to something within your skill level and work your way up from there. Good luck!
<-- Spell based team dueling game!
