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