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