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