Unlock Cars:
Platform: PSP
The following cars are unlocked for purchase in order.
Volkswagen Golf GTI 2.0L: $22,000
Ford Focus ZX3: $18,000
Mazda Miata MX-5: $19,000
Dodge Neon: $17,000
Nissan Sentra SE-R SPEC-V: $21,000
Toyota Celica GT-S: $23,000
Nissan 240SX: $30,000
Mitsubishi Eclipse GSX: $32,000
Mazda RX-7: $34,000
Mazda RX-8: $48,000
Pontiac GTO: $46,000
Subaru WRX STi: $46,000
1969 Dodge Charger: $44,000
Toyota Supra: $52,000
Nissan 350Z: $54,000
Mitsubishi Lancer: $51,000
Ford SVT Mustang Cobra R: $56,000
1967 Ford Mustang: $65,000
Nissan Skyline R34 GTR: $70,000
Chevrolet Corvette Z06: $72,000
Infanite noz(boost)
Platform: PSP
At selection screen press Down, Circle, Circle, Up, Square, Circle
More parts for your vehicle
Platform: PSP
On any race set, complete the last race in that event with a gold medal and you will unlock bonus parts for your vehicle.
Nitrous Glitch
Platform: PSP
In drag racing if you tap the nitrous button instead of holding the button down your car will accelerate at a faster speed
Computers and Shortcuts
Platform: PSP
In Lincoln Connector an easy way to win is to simply force the computer into the first shortcut of the race. Once the computer is in the shortcut the car will freeze for a period of time. This freezing can even last for up to a lap.
Fast Mazda RX-7:
Platform: PSP
After getting the RX-7, put the following upgrade parts on the car to obtain maximum speed: Aeromax spoiler, Beast Carbon Fiber hood, Gills roof scoop, and Max 1 body kit. Also, make sure you all of the performance upgrades unlocked and ready to install. You can get over 210 mph with this setup and win won a race by 42 seconds.
Avoid losing control:
Platform: PSP
Press R1 before you hit a wall or you might lose control.
Car selection:
Platform: PSP
If you are having trouble figuring out which cars to use for what event, cars with high top speeds/acceleration are good for drag races; cars with good controls/handling are best for drifting; and cars with a balance of the three are good for normal racing.
Earning driver points:
Platform: PSP
You can earn all the upgrade points in an event by winning it in Bronze and Silver difficulty settings. However, to get all of the driver points you must win all of the races under the Gold difficulty setting. Check the "Driver Status" screen in "My Underground" to see your current driver points and driver rank. Maxing out your driver rank will unlock secret bonuses.
Boss cars:
Platform: PSP
Some race events are listed as "Boss Race" in the event description. Win that event under the gold difficulty setting to be awarded that Boss's car (1969 Dodge Charger, Subaru Impreza WRX STi, Chevrolet Corvette Z06 and Nissan Skyline R34 GTR). When you win a Boss car, it will appear in the Pocket Garage, and you can race it in any game event.