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