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