This is some sort of promotional thing run by Certified Locals. I went to the first one in Erskineville and the queues weren't very long, though you will be given a short spiel and a card by one of the Certified Locals representatives while you wait.
You should remember that at the moment, E10 is around 129.9 so if you drive a medium to large sized car, all you will be saving is around $20-$30. If you'll be driving from west of Petersham, south of Brighton-Le-Sands or north of Crows Nest to get this, you'll potentially wipe the savings out on the trip to Rose Bay. However, if you live in Bondi and your Mercedes S600 needs a fill up of cheap 98, this is a great deal for you.
Good price but too far for me