Go to "quick race" then when selecting a car, push the up butto until it says "Bonus Cars" in the bottom right (to the left of the car name) and the Audi Le mans quattro will be there with two versions, one is Darius' the other is this ugly yet cool light blue and white. And yeah, you can't customize it and that sucks, its just like the BMW in Most Wanted (which you can unlock in this game, so maybe the Le mans will be unlockable in the next one).
Which is worse? Being hole-punched to death or being eaten alive by the cast of "Friends"?