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