The Car Wash Add-on for Gas Station Simulator has 10 achievements.
Fed the Sewer Alligator
Unlocked the Car Wash
Upgraded the Car Wash to Level 2
Upgraded the Car Wash to Level 3
Upgraded the Car Wash to Level 4
Upgraded the Car Wash to Level 5
Washed 1 Car
Washed 10 Cars
Washed 50 Cars
Returned the fish to their "natural" habitat.