Here is the full list of all 39 Pixel Traffic: Circle Rush achievements. It takes around 2-3 hours to unlock all of the achievements on Windows.
Collect all cars
Unlock bus
Unlock racing car
Unlock coupe car
Unlock cabrio car
Unlock cruiser car
Unlock offroad car
Unlock hyper car
Unlock advanced racing car
Unlock advanced cabrio car
Unlock formula racing car
Unlock super mini car
Unlock racing kart
Unlock truck
Unlock tuned coupe car
Unlock tuned mini car
Unlock super mini sport car
Unlock advanced racing kart
Unlock muscle car
Unlock advanced formula racing car
Unlock advanced classic car
Unlock tuned offroad car
Unlock concept car
Unlock advanced muscle car
Unlock advanced concept car
Unlock police car
Unlock advanced hyper car
Unlock battle tank
Unlock advanced cruiser car
Save 1000 coins
Save 2000 coins
Save 3000 coins
Unlock mini car
Don't use breaks for 15 laps
Drive your car 20 laps
Drive your car 15 laps
Drive your car 10 laps
Don't stop accelerating for 5 laps
Unlock tank