Here is the full list of all 38 GRID (2019) achievements.
Drive a total distance equal to the circumference of the Earth
Earn a gold trophy in every Career Event in the Career Tab
Complete every Career Event in the Stock category
Win a race in a Ravenwest livery with Nathan McKane as your team mate
Complete every Career Event in the FA Racing category
Win the 'Showdown: Ravenwest' Career Event
Complete every Career Event in the GT category
Win an Event with a full grid having finished the first round in last place
Win the 'Showdown: Aurora Motorsport' Career Event
Complete every Career Event in the Invitational category
Reach Player Level 99
Own at least one car in each class available from launch
Win an Event with at least 3 other racers using a loan car
Win the 'Showdown: Fernando Alonso' Career Event
Win a race by crossing the line backwards
Complete every Career Event in the Tuner category
Gain entry to the GRID World Series
Win the 'Showdown: Vulpini Racing' Career Event
Win the 'Showdown: Euro Rand' Career Event
Win the 'Showdown: DisruptR' Career Event
Reach player level 50
Finish a race with at least 3 other racers without taking any damage
Customise your first livery
Complete every Career Event in the Touring category
Win the 'Showdown: Hammerhead' Career Event
Win your first Career Event
Beat your first Career Rival
Beat your first Nemesis
Purchase your first car