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