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 achieved a podium in the Champion final
You wrecked 20 vehicles in the Lafayette Eulogy
You completed a Showdown Tour event in each location
You own 15 vehicles
You reached Fanbase Level 30 Online
You reached Fanbase Level 20 Online
You reached Fanbase Level 10 Online
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 achieved a podium in the AllStar final
You Dominated the track on the final lap
You pulled it together and pulled the opposition apart to achieve a podium in the Showdown Tour
You survived for 2 minutes or more in Hard Target
You achieved a 5x Wrecking Streak in Rampage
You came 1st in a Smash Hunter event
You achieved a podium in the Pro final
You won a Race-Off event without boosting
You fully upgraded a vehicle
You dominated a friend in Challenge mode
You completed a Splitscreen event
You used all your boost in one go and kept out of trouble
You pulled off an Insane T-Bone
You viewed a Crashback replay
You were in 1st at each Elimination period
You completed a Race-Off, Rampage and Head 2 Head event
You completed a clean Head 2 Head run
You took on and beat a friend's Challenge
You got the First Blood bonus
You wrecked your first opponent in Rampage
You completed your first Showdown Tour event
You sent a Challenge to a friend
Collect all 100 Hidden Packages in Joyride
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
Achieve all hit types in Rampage
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
Complete 100% of the Battersea Compound Missions
Complete 100% of the Yokohama Compound Missions
Achieve a podium in the Legend final
Complete all Joyride Missions in both locations
Fully upgrade all vehicles
Complete the Showdown Tour and win Gold in every event