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