Siren:
Set the rear spoiler to type 5 for the R30 and R30M, then use the horn. 

New nickname:
Select any team sticker for your car and the team will get a new nickname. 

Car part preview:
Select the exhaust or aero at the parts selection screen. Press Triangle as the view 
zooms in to keep the camera away from the car. Press Triangle again to resume 
the zoom.

Dog decoration:
Hold L1 + X + Circle when choosing your shift assist option. Keep the buttons held 
until the game has competed loading. A dog with horns will be hanging from the 
roof of your car in the first person view. 

Full pause screen:
Pause the game and press Triangle + Square. Press Triangle + Square again to 
restore the pause screen. 

Analyze option:
Pause the game immediately when you start a drive in quest mode. Scroll all the 
way down the pause menu to access an "Analyze" option under "Retire". This 
allows you to see the turning rate, accelerator, and brake pressure. This only 
works at the very start of the drive and you cannot turn it off once enabled. 
Note: This may be dependent on the car type or parts. 

Delete scores:
At time record screen, hold L1 + L2 + R1 + R2 and press Start. 

Blue mosquito decoration:
Hold L2 + X + Circle when choosing your shift assist option. Keep the buttons held 
until the game has competed loading. A blue mosquito with yellow sunglasses will 
be hanging from the roof of your car in the first person view. 

Genki Gremlin decoration:
Hold R2 + X + Circle when choosing your shift assist option. Keep the buttons held 
until the game has competed loading. The Genki Gremlin will be hanging from the 
roof of your car in the first person view. 

Fixed replay view:
Hold Triangle when the replay is about to start. 

Control replay view:
Start a replay in the driver view position, then press L1 or R1 to pan the camera. 

View free run positions:
At the course selection screen in free run mode, press Square to see the other 
cars. 

View one-on-one battle positions:
During a one-on-one battle, press Square to see the positions of all other cars. 

Display replay meters:
During a replay, press Select. 

White Carismo car:
Defeat the last Zodiac (White Carismo) to unlock his car and get about $4 million 
dollars. To get $5 million dollars when you defeat White Carismo, let him win the 
first time he challenges you. Then go up, challenge him, and win. At the ending 
you will see a message appear that saying "Challenge Ending = 5 Million Dollars". 

Pink creature decoration:
Hold R1 + X + Circle when choosing your shift assist option. Keep the buttons held 
until the game has competed loading. A pink creature will be hanging from the roof 
of your car in the first person view. 

Alternate loading sequence:
Hold R1 while selecting a transmission type. Keep R1 held through out the loading 
screen to see a man hanging from the roof of your car in first person view. 

Mirror Buddies:
While you are at the screen where you pick your transmission hold either 
r1,r2,l1,l2 until the now loading screen comes up. While your driving there will be a 
little beanie buddy next to your rear view mirror. 

3 Million Dollars:
Beat the Speed King. He drives the 1200 HP Skyline. You will get 3 million dollars 
and the ability to buy his car. It's not easy. 

Skyline car:
Defeat the Speed King to get $3 million and unlock the Skyline car for purchase