Activate the following cheats by entering the corresponding codes at "Options" > "Secret Codes". Each code will work once per profile. The bonus cars are only available in Quick Race mode:

CHEAT FUNTION - CHEAT CODE
$10,000 - %%$3/"
Die-Cast Lexus IS F bonus car - 0;6,2;
Die-Cast Nissan 240SX (S13) bonus car - @/;#/+
Die-Cast Volkwagen R32 bonus car - !3/$"):
NeedforSpeed.com Lotus Elise bonus car - -KJ3=E
T-Mobile give's you $15,000 money - S1D3K1CK
Unlocks Die-Cast Audi R8 Bonus Car - )B7@B=
Unlocks Die-Cast Camaro Concept Bonus Car - !K?MMF0
Unlocks Die-Cast Dodge Charger Bonus Car - qlcukc4bqm
Unlocks Die-Cast Dodge Viper SRT10 Bonus Car - !C6;C>E
Unlocks Die-Cast GT-R Police Bonus Car - "90=*6@
Unlocks Die-Cast Mitsubishi Lancer Bonus Car - 2<?P;G
Unlocks Die-Cast Pontiac GTO Bonus Car - d5dviyrlgn
Unlocks Die-Cast Posche 911 Turbo Bonus Car - >8P:I;
Unlocks Shelby Terlingua Bonus Car - NeedForSpeedShelbyTerlingua

To evade a police pursuit, cross the bridge located at the lower right-hand corner of the map by the stadium. The cops will not cross this bridge.

Unlock the police car to unlock Chasedown mode. Then, ram the car until it is disabled. You will receive between $19,000 to $22,000.

To get a boost at the start of the race, move the RPM into the blue right when the race starts.

Unlock the following cars by performing the corresponding tasks:

CAR - HOW TO UNLOCK
Battle Machine RX-7 - Win the first 30 challenge series events.
Dominator Corvette Z06 - Dominate over 30 challenges series events.
Speed Machine 911GT2 - Win all 60 challenge series events.