Here is the full list of all 46 Car Mechanic Simulator 2021 achievements. It takes around 120-150 hours to unlock all of the achievements on Windows.
Visit Barn 30 times
Buy 30 cars from junkyard
Paint 60 cars
Buy 25 cars from impact cars
Renovate and sell 50 cars
Reach level 50
Unlock 10 parking alleys
Buy new car in car salon
Finish lap with time under 1:50
Finish 100 orders
Buy 5 cars from impact cars
Finish path test 25 times
Buy 30 cars from barn
Finish all the special missions
Unscrew 10 000 bolts
Swap engine
Unlock all upgrades
Buy 3000 parts from main shop
Balance 50 tires
Earn 2000 scrap parts
Paint 5 cars
Sell 1000 parts from inventory
Fix 150 body parts
Reach level 3 of garage expansion
Renovate and sell 1 car
Earn 5000 CR on sell cars
Earn 50 000 CR on sell cars
Finish test track
Fix 50 body parts
Buy 1 car from barn
Visit Barn first time
Earn 500 scrap parts
Pour old oil on the floor
Reach level 20
Fix 150 car parts
Finish path test first time
Fix 50 car parts
Buy 1 car from junkyard
Visit a junkyard
Buy 100 parts from main shop
Reach level 5
Finish order with experience bonus
Finish order with money bonus
Finish 1 order
Balance 5 tires
Visit Salon