Full list of all 49 DiRT Showdown achievements worth 1,000 gamerscore. It takes around 25-30 hours to unlock all of the achievements on Xbox 360.
You Dominated the track on the final lap
You fully upgraded a vehicle
You completed a Splitscreen event
You used all your boost in one go and kept out of trouble
You reached Fanbase Level 30 Online
You took on and beat a friend's Challenge
You achieved all hit types in Rampage events
You completed a Race-Off, Rampage and Head 2 Head event
You wrecked your first opponent in Rampage
You pulled off an Insane T-Bone
You won an Online event as part of a team
You dropped the Flag off 5 times in a Transporter event
You kept hold of the Loot for 2 minutes in Smash & Grab
You won a Speed Skirmish event
You sent a Challenge to a friend
You got the First Blood bonus
You reached Fanbase Level 20 Online
You reached Fanbase Level 10 Online
You completed your first Showdown Tour event
You viewed a Crashback replay
Complete a clean run in a Head 2 Head event
Be in 1st place during each elimination period in an Eliminator event
Win a Smash Hunter event
Achieve a podium in the Pro final
Be in last place and then earn a podium during double points in a Rampage event in the Showdown Tour
Complete a Showdown Tour event in each location
Own 15 vehicles
Win a Race-Off event without boosting
Achieve a podium in the AllStar final
Achieve a podium in the Champion final
Collect all 100 Hidden Packages in Joyride
Wreck 20 vehicles in the Lafayette Eulogy
Complete the Showdown Tour with at least a Bronze in every event
Own every vehicle in the game
Complete 50% of the Yokohama Compound Missions
Complete 50% of the Battersea Compound Missions
Score 300,000 points in a Trick Rush event in the Showdown Tour
Complete the Donut King Mission in the Yokohama Construction Site area
Earn a total of $1,000,000
Complete the Showdown Tour with at least a Silver in every event
Survive for at least 2 minutes in a Hard Target event
Achieve a 5x Wrecking Streak in Rampage
Complete 100% of the Battersea Compound Missions
Complete 100% of the Yokohama Compound Missions
Achieve a podium in the Legend final
Dominate a friend in Challenge mode
Complete all Joyride Missions in both locations
Fully upgrade all vehicles
Complete the Showdown Tour and win Gold in every event