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