Here is the full list of all 30 Carmageddon: Max Damage achievements worth 1,000 gamerscore.
Killed 16,666 Peds
Wrecked 100 Opponents in Car Crusher
Been the Fox for half an hour in Fox 'n' Hounds
Completed 60 Laps in Death Race
Finished one Classic Carma Event in all three ways
Completed the Up Your Carma Mission
Completed the Ped Popper Mission
Completed the Bulging Purse Mission
Completed the Hotwiring Hotstuff Mission
Completed 63 different Career Events on any Difficulty
Completed the Mile Muncher Mission
Finished a Classic Carma Event by Killing all the Peds
Achieved 60 Cunning Stunts
Bought and Equipped 12 Parts in the Parts Shop for one Car
Finished a Classic Carma Event by Completing all the Laps
Unlocked Chapter 10 in the Career
Hit 100 Checkpoints in Checkpoint Stampede
Killed 50 targeted Peds in Ped Chase
Completed the They Don't Like It Up 'Em Mission
Got a x10 Ped Kill Combo
Completed the Split Personality Mission
Customised your car by visiting the Parts Shop and buying a part
Achieved a Suck My Parts or Collateral Damage Bonus
Unlocked Chapter 2 in the Career
You completed the tutorial. You swot
Finished a Classic Carma Event by Wrecking all the Opponents
Wrecked your first Opponent
Complete the MultiSlayer Mission
Collect 55 Smelly Bushes
Complete the MP MegaPeep Mission