Here is the full list of all 20 Asphalt 8: Airborne achievements worth 200 gamerscore.
Fully upgrade 3 cars
Acquire 10,000 credits during a single race
Fully upgrade 1 car
Beat Season 1
Have 10 cars
Fully upgrade one stat of any car
Total 10 minutes of air time!
Knock down the same car 5 times in a single race
Win a race without using Nitro
Have 50 Stars
Drift 10 km
Execute 25 Knockdowns
Come in last place
Perform 20 Perfect Nitro boosts
Buy your first car upgrade
Get 1st place
Earn 10 medals during a race
Buy a new car
Drift 1 m
Complete all seasons