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