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