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