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