Activate the following cheats by entering the corresponding codes at "Main Menu" > "Options" > "Cheat Codes":

CHEAT FUNCTION - CHEAT CODE
Arcade Mode Events - SLVRKEY
Lightning McQueen Custom Kit Parts - GR8MODS
Lightning McQueen's Friends - EVRYBDY
Paint Jobs for all Non-Lightning McQueen's Characters - CARSHOW
Story Mode Events - GOLDKEY

ACHIEVEMENT - HOW TO UNLOCK
PLUGGIN' AWAY! (25 points) - Collect all spark plugs from all races.
Mini Master! (25 points) - Win all Mini-Game events.
TEAM PLAYER! (25 points) - Win all Academy Challenges.
Big Ham! (25 points) - Beat all Photo Ops.
Mack Track Medalist! (25 points) - Score 4000 points in the Mack Track Challenge event.
Daring Devil! (50 points) - Score 5500 points in the Mater the Greater event.
Ole'! (50 points) - Score 25000 points in the Materdor event.
Tokyo Triumph! (50 points) - Score 25000 points in the Tokyo Mater event.
Drift Master! (25 points) - Score 4500 points with a single drift.
Crowned Karter! (25 points) - Win all Guido Kart events.
Luigi's BFF! (25 points) - Win all Tire Find events.
A Real Go Getter! (25 points) - Win all Transporter events.
Perfectionist! (25 points) - Win all Autocross events.
Mooo-ving Along! (25 points) - Win all Tractor Stampede events.
The Law! (25 points) - Win all Sheriff's Pursuit events.
Podium Perfection! (25 points) - Win all circuit race events.
Sprinter! (25 points) - Win all Point to Point Race events.
Santa Carburera Champ! (100 points) - Beat Candice.
Big City! (100 points) - Beat Stinger.
Autovia Avenger! (100 points) - Beat El Machismo.
The Champ! (100 points) - Beat Chick Hicks for the Title.
OVER ACHIEVER! (100 points) - Earn all achievements.