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