Bonus cars - Successfully complete the indicated task to unlock the corresponding car:

Police Austin Mini Cooper: Win Easy Race mode with the Austin Mini Cooper.
Police Fiat A112 Abarth: Win Easy Race mode with the Fiat A112 Abarth.
Police Lancia Delta: Win Easy Race mode with the Lancia Delta.
Police Renault 5: Win Easy Race mode with the Renault 5.
Police Volkswagen Golf GTI: Win Easy Race mode with the Volkswagen Golf GTI.
Taxi Austin Mini Cooper: Win Medium Race mode with the Austin Mini Cooper.
Taxi Fiat A112 Abarth: Win Medium Race mode with the A112 Abarth.
Taxi Lancia Delta: Win Medium Race mode with the Lancia Delta.
Taxi Renault 5: Win Medium Race mode with the Renault 5.
Taxi Volkswagen Golf GTI: Win Medium Race mode with the Volkswagen Golf GTI.
Toy Dog: Win Hard Race mode with any car.

Trophies - Successfully complete one of the following tasks to get a trophy:

Photo Finish (Bronze): Finish in first position less than 0.1 seconds ahead of an opponent.
L Plates (Bronze): Finish any race (Single Player).
Back At Ya (Bronze): Pass the bomb back to a player within 5 seconds of receiving it (Multiplayer).
Bombtag Bully (Bronze): Pass the bomb to the same player 3 times in 1 game (Multiplayer).
Rolling On Suds (Bronze): Clean your car in the car wash and finish a race (Single Player).
Me First (Bronze): Finish each lap of a race in 1st position (Single Player).
Exhibit (Bronze): Customize a car.
Dented Pride (Bronze): Win a race after crashing into all opponents at least once (Single Player).
Solo Polo (Bronze): Car Pack Trophies. Win 5 Races using the VW Polo.
Scorpion Fight (Bronze): Car Pack Trophies. Win 5 Races using the Fiat 500 Abarth.
French Fancy (Bronze): Car Pack Trophies. Win 5 Races using the Peugeot 207 GT.
Minitastic (Bronze): Car Pack Trophies. Win 5 Races with the Mini Cooper 2007.
Common Courtesy (Bronze): Car Pack Trophies. Complete 5 Races without crashing (Single Player).
New Breed (Bronze): Car Pack Trophies. Win 2 Easy Races with each of the new cars (Single Player).
Born Winner (Bronze): Car Pack Trophies. Win 2 Medium Races with each of the new cars (Single Player).
Pro (Silver): Win a hard race (Single Player).
Showboating (Silver): Finish first whilst reversing over the line (Single Player).
Don't Stop Me Now (Silver): Finish a race in the top 3 without using the brake or handbrake (Single Player).
Top Dog (Silver): Car Pack Trophies. Beat the fastest time for a Hard Race in the Records (Single Player).
Impossible Turnaround (Silver): Car Pack Trophies. Win a Hard Race after finishing your 1st lap in last place (Single Player).
Leader of the Pack (Silver): Car Pack Trophies. Win 3 Hard Races with each of the new cars (Single Player).
Speed Demon (Gold): Complete a lap in less than 37 seconds and finish a race (Single Player).