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