Full list of all 38 GRID achievements worth 1,315 gamerscore. It takes around 200-300 hours to unlock all of the achievements in the base game on Xbox One.
The base game contains 29 achievements worth 1,000 Gamerscore, and there are 3 DLC packs containing 9 achievements worth 315 Gamerscore.
Reached Player Level 99
Purchased at least one car in each class
You won a race in a Ravenwest livery with Nathan McKane as your team mate
Won the 'Showdown: Ravenwest' Career Event
Earned a gold trophy in every Career Event
Completed every Career Event in the FA Racing category
Won the 'Showdown: Fernando Alonso' Career Event
Completed every Career Event in the Invitational category
Won the 'Showdown: Aurora Motorsport' Career Event
Completed every Career Event in the Stock category
Won the 'Showdown: Vulpini Racing' Career Event
Gained entry to the GRID World Series
Completed every Career Event in the GT category
Won the 'Showdown: Euro Rand' Career Event
Reached player level 50
Completed every Career Event in the Tuner category
Won an Event having finished the first round in last place.
Won an Event with at least 3 other racers using a loan car
Completed every Career Event in the Touring category
Finished a race with at least 3 other racers without taking any damage
Won the 'Showdown: Hammerhead' Career Event
Won the 'Showdown: DisruptR' Career Event
Won a race by crossing the line backwards
Beat your first Nemesis
Beat your first Career Rival
You customised your first livery
Purchased your first car
Won your first Career Event
Drive a total distance equal to the circumference of the Earth
Achieved the Fast for a Hatchback Objective
Achieved the High Altitude Objective
Achieved the Delta Time Objective
Achieved the Burning Rubber Objective
Achieved the British Heritage Objective
Complete the A Wheely Good Time Objective
Achieved the Gone in a Flash Objective
Achieved the Painting the Track red Objective
Complete the Flights to Catch Objective