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