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