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