A news article in The Sydney Morning Herald Sydney reported that “Sydney is by far the cheapest Australian city to buy petrol, with pump prices dropping by 4.2 cents per litre in the past week. The national average for unleaded petrol eased 0.8 cents per litre to 128 cents, the Australian Institute of Petroleum said in its latest weekly report released on Monday.  The metropolitan average fell 1.2 cents per litre to 127.3 cents, led by the sharp fall in Sydney, while the regional average eased 0.2 cents per litre to 129.3 cents.”
My experience so far is that the above prices are generally petrol pump prices in major petrol stations like Shell, Caltex, BP, or Mobil. Petrol prices from independent retailers that are normally located in most Sydney suburbs is cheaper by few cents.
While some major groceries like Coles and Woolworths offers petrol discount vouchers, I do not find it useful because their participating petrol stations are limited. One funny experience I had was with my Woolworth Everyday Reward Card which offers 5 cents off petrol. I went to a Caltex station to avail such discount and confidently,  I hand in my everyday reward card to the attendant at the payment counter. I must mention that the Caltex logo appears on the reward card. But to my surprise, the attendant tactfully adviced that only Caltex operated by Woolworth honor such card! Their Caltex station is not one of them. How will I know? There’s no way I can tell. Whew! I was misled by the logo to be honest. So, I just smiled and walked away as if nothing had happened.