There simply must be some cheats for PSP Disney/Pixar Cars!!?

Question

I've only found one which is hold L button and enter X, Square, Triangle, X, Triangle, Square to unlock a bonus Speedway reversed track. But that's not my point. My point is that I can only find unlockables, but what I want is HOW to unlock them! I cannot - no matter what - win Turbine Canyon! It took me ages to finish Mesa Ravine, and I'm stuck again.
Anyone ho can find any more cheats, I will be forever grateful (and so will my thumbs!).

Please note: I want cheats for PSP, no other platform.

Answer 1

Here are some

http://www.acheatcodes.com/cheatcodes/site/search/22184/PSP/Cars

And for links to others you might try here - http://psp.gamezone.com/gamesell/hints/h28727.htm