Here is the full list of all 30 Carmageddon: Max Damage achievements.
Collect 55 Smelly Bushes
Kill 16,666 Peds
Complete the Up Your Carma Challenge
Complete the MP MegaPeep Challenge
Complete the MultiSlayer Challenge
Complete the Ped Popper Challenge
Complete the Hotwiring Hotstuff Challenge
Be the Fox for half an hour in Fox 'n' Hounds
Complete the They Don't Like It Up 'Em Challenge
Finish one Classic Carma Event in all three ways
Finish a Classic Carma Event by Killing all the Peds
Complete 63 different Career Events on any Difficulty
Wreck 100 Opponents in Car Crusher
Complete the Mile Muncher Challenge
Complete the Bulging Purse Challenge
Buy and Equip 12 Parts in the Parts Shop for one Car
Unlock Chapter 10 in the Career
Kill 50 targeted Peds in Ped Chase
Achieve 60 Cunning Stunts
Hit 100 Checkpoints in Checkpoint Stampede
Achieve a Suck My Parts or Collateral Damage Bonus
Complete 60 Laps in Death Race
Complete the Split Personality Challenge
Customise your car by visiting the Parts Shop and buying a part
Finish a Classic Carma Event by Completing all the Laps
Get a x10 Ped Kill Combo
Unlock Chapter 2 in the Career
Finish a Classic Carma Event by Wrecking all the Opponents
Wreck your first Opponent
Own Carmageddon Max Pack, Carmageddon 2: Carpocalypse Now and "the other one"...