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