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