Here is the full list of all 60 DiRT 3 Complete Edition achievements. It takes around 50-60 hours to unlock all of the achievements on Windows.
Achieve first place finishes in all DiRT Tour events
Complete a Time Trial race in a vehicle from each class of Rally
Complete all Gymkhana Championships
Complete a Steam multiplayer race with a ‘Cautious’ rating
Drive in excess of 100 miles (161 km) in Monte Carlo
Drive all of the cars from the Mud and Guts Car Pack
Win a DIRT Tour event in a car from the Power and Glory Car Pack using a custom setup
Drive all of the cars from the Power and Glory Car Pack
Complete all of the DC Challenges
Achieve Silver medals in all of the DC Challenges
Achieve Gold medals in all of the DC Challenges
Achieve Platinum medals in all of the DC Challenges
Complete a clean run in a Gymkhana Sprint DC Challenge
Achieve first place finishes and pass the DC Challenge in a World Tour event
Complete 100% of the Battersea Compound Missions
Complete a Time Trial in Shibuya
Win the DC SuperSeries Championship
Achieve first place in all DiRT Tour Monte Carlo Events
Win a DiRT Tour race without using any driver assists
Reach Driver Rep Level 30
Achieve first place in all DiRT Tour Shibuya Events
Complete 75% of the Battersea Compound Missions
Achieve a podium finish in the Winter X Games Tournament
Beat the Bobsleigh in the Norway Speed Run DC Challenge
Score 500,000 Points in a Gymkhana Event
Ace all trick types in a Gymkhana Championship event
Win a DiRT Tour race in the Mini Cooper without receiving any damage
Win a Rally race in the DiRT Tour using the interior camera and the HUD switched off
Smash every robot in a Smash Attack DC Challenge
Use a flashback in the DiRT Tour after receiving terminal damage and then go on to win the race
Achieve a Platinum medal in all of the Gymkhana Academy tutorials
Win a game in each of the multiplayer party modes (Pro Tour or Jam Session)
Win a Steam race in Shibuya (Jam Session)
Complete 50% of the Battersea Compound Missions
Reach Driver Rep Level 20
Achieve a podium finish in the X Games Tournament
Win DiRT Tour races using vehicles from each discipline
Complete 25% of the Battersea Compound Missions
Be the mouse in a Cat n Mouse game where your team has gone on to win the game (Jam Session)
Win a race in every location
Complete 25 bonus Race Objectives
Win a DiRT Tour race in a Rally car from each decade
Score 25,000 drift points in a Drift Showcase DC Challenge
Complete a clean race with a car from the Mud and Guts Car Pack
Win a Steam race in Monte Carlo (Jam Session)
Win a race in all weather conditions
Win 10 Steam games (Pro Tour or Jam Session)
Achieve a podium finish in the Gymkhana Academy
Reach Driver Rep Level 10
Complete the tutorials in the Gymkhana Academy
Complete 25 Steam games (Pro Tour or Jam Session)
Remain uninfected in a round of Outbreak (Pro Tour or Jam Session)
Complete 5 bonus Race Objectives
Complete your first DiRT Tour race
Complete a Joyride online with at least 3 other players
Complete your first Pro Tour race on Steam
Complete a game of Invasion without any negative points (Pro Tour)
Steal the flag from the opposing team 5 times in a game of Transporter (Pro Tour)
Win a Steam race in Hardcore Mode
Earn enough fans to achieve the ‘Superstar’ title