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