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