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