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