Here is the full list of all 45 Flatout 3: Chaos & Destruction achievements.
Kill one zombie.
Win a Monstertruck challenge.
Win all races.
Win all Detroit races.
Win all Vienna races.
Win all Rome races.
Win all Outdoor races.
Win all Uranium Mine races.
Win all Harbor races.
Win a Golf stunt.
Win an Industrial stunt.
Win a Nightmare stunt.
Win a Nightshift race.
Win all Nightshift races.
Finish a Nightshift race as loser.
Win all Monstertruck challenges.
Win all normal Battle Arenas.
Win all Big Battle Arenas.
Win all Kansas Offroad races.
Win all Utah Offroad races.
Win on a Speed track.
Win all Speed tracks
Complete all stunts.
Win a race.
Win a normal Battle Arena match.
Win a Big Battle Arena match.
Win all Offroad races.
Win on a reversed track.
Play a multiplayer game.
Be destroyed by a train.
Drive into water.
Complete a challenge.
Complete 25 challenges.
Complete all challenges.
Score a 10 hit combo.
Score a 20 hit combo.
Score a 30 hit combo.
Score a 40 hit combo.
Score a 50 hit combo.
Score a 60 hit combo.
Get a score of 7 million.
Complete all splatout levels.
Kill 10000 zombies.
Score a 100 hit combo.
Score a 150 hit combo.