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