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