Here is the full list of all 12 WRC Powerslide achievements. It takes around 8-10 hours to unlock all of the achievements on Windows.
Win a Special Stage in Single Player mode
Use the "Cloud" Power-Up in a Special Stage in the Wales Rally GB
Use the "Flatout" Power-Up 3 times in the same race
Use the "Horn Power" Power-Up 3 times in the same race
Use the "Extreme Pace" Power-Up 10 times in total
Use the "Thunder Bolt" Power-Up 10 times in total
Use the "Hailstorm" Power-Up 10 times in total
Win all the gold medals in the "Vodafone Rally de Portugal"
Win all the gold medals in the "Rallye de France - Alsace"
Win all the gold medals in the "Rally Guanajuato Mexico"
Reach a total of 45 minutes of racing in valid Online games
Complete the Single Player mode to 100% and win the final cup!