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