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