Victoria's current average unleaded price of $1.85/L is made up of roughly: 80¢ for refined fuel, 50¢ federal excise, 22¢ GST, and the remainder covering distribution, retailer margin, and any metro price cycle premium.
GasBuddy and RACV track Melbourne's price cycle weekly. Understanding the local pricing dynamic can save a typical Victoria driver $300–$500 per year simply by timing fill-ups correctly.
If you drive the Australian average of ~15,000 km/year in a 7.5 L/100km car, you spend approximately $2,081 on petrol at the current VICprice. That's before any savings from timing the cycle.