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