Ending Bonuses:
Complete the game to unlock the Free Run mode which has no cars on the raod, Free Run Twin mode (Two palyer) and a Credits option. 

Face off mode: 
Compelte the championship mode to ulock the face off mode against the Roadest

Unlock Vehicles:
Unlock these vehicles by beating them in Face Off mode. 

Face Off 1: Roadster
Face Off 2: Towtruck
Face Off 3: Saloon GT
Face Off 4: Bus 

Quick Start:
Accelerate immediately before the "1" fades during the pre-race countdown to get a slight speed boost. 

Full Bonus:
Drive a perfect lap (no accidents) and your bonus will be automatically filled.