Motion blur mode
Press Up, Left, Circle, Down, Right, Square, Up, Down, Left, Right, Circle, Square at the main menu to unlock "Motion Blur" in options menu
Alternate paint job
Press Down, Square, Down, R1, Right(2), Up, Left, Circle(2), L2, L1 at the main menu. This will change the paintjob of your car when you begin a game
Unlock The Geeze Car
Collect all the coins in Rome Level 1
Unlock the P-Nut car
collect all the coins in Rome Level 2
Unlock the Froggy Car
Collect all the coins in Rome Level 3
Unlock Super Genius Car
Collect all the coins in London Level 1
Unlock the Turtle Car
Collect all the coins in London Level 2
Unlock the Ricochet Car
Collect all the coins in London Level 3
Unlock Fang Car
Collect all the coins in London level 4
Unlock Road Shark car
Collect all the coins in London Level 5
Unlock Portabello car
Collect all the coins in Tokyo Level 1
Unlock Street Eagle Car
Collect all the coins in Tokyo Level 2
Unlock Black Widow Car
Collect all the coins in Tokyo Level 3
Many of the cars you unlock more than resemble real car models... Here's a list of the cars that resemble real cars
Turtle car = VW Beetle Convertible
Ricochet car = Audi TT
Fang car = Mazda MR2 Spyder
Road Shark car = Honda S2000
Portabello car = Lotus Elise
Street Eagle car = Porsche 911
Black Widow car = Plymouth Prowler