At the main menu, press [R1], [R2], [L1], [L2], [R1], [R2], [L1], [L2] to display the cheat entry option. Then, use the onscreen keyboard to enter one of the following codes to activate the corresponding cheat function:

WORLD CHAMP - All bonuses
AUTO PILOT - Auto-pilot (press [R3] during a race to activate it)
BOOST - Boost in all events (press [L3] during a race to activate it)
ENERGY - Mega-boost in all events (press [R3] during a race to activate it)
SPEEDFREAKS - Most events and full TT course (except the Mad Sunday events)
FUNKY MOPEDS - All bikes
GOODIES - All collection book items
BONE DOME - All helmets
GRAVEL RASH - All leathers
HOOPS - All wheels
WINGS - Mad Sunday events