The RC Buggy Is The Portal Car.
Basically It Let's You Travel To A Glitch Inside The Game.
You Must Have Completed The Game 100%,Then Use The A,B,A,B Cheat
In The Option Menu At The Main Screen.
To Activate The Cheat Go To One Of The Phones In The Game And Use L Or R Trigger.
To Enter Got To Some Water And Use The Jump Cheat (On The Cheats Page On Cheats Guru For This Game).
Them Be Amazed!