Cars

To unlock this achievement you must unlock the Tailfin Pass area in the game.

To unlock the Tailfin Pass area in the game you will have to finish in all 20 previous races (7 races in chapter one, 6 in chapter two, 6 in chapter three, and 1 in chapter four). So Tailfin Pass area will unlock (and so will your achievement) once you finish the first race in chapter 4.

I don't think any of the races where that hard to do but if you want to make things easier and faster I would suggest using the cheat codes (you will still get your achievements). I recommend only doing "VROOOOM" and "IMSPEED" since I am not sure if the others affect achievements and they will not help you at all. The cheat codes are found here:

http://vgstrategies.about.com/od/xbox360cheatsc/a/CarsC....htm