MotorMouth
Anywhere from AU$1.10 - AU$1.55 a litre (US$3.15- US$$4.45 a US gallon) currently. Remote or Northern Territory non urban prices can easily be 25% more than that top.
Most gas (called petrol here) is imported from Singapore these days as Australia's aging and decrepit small refineries have run down, closed or been mothballed. Australia has very little stocked reserves - about 20 days maximum, nothing like the mandated requirements in the US. All fuel for road use is taxed twice.
All retail fuel prices in Australia include GST at the rate of 10 per cent (or 1/11th of the total price paid). For unleaded petrol (regular or premium grades) and diesel the price you pay includes Australian Government excise of
38.60 cents per litre (cpl) which is an automatically inflation indexed tax.
Offroad farm and mining use of diesel is exempt from the 38.6 cents excise but still pays the 10% GST.