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