**In short: **
The government has halved the fuel excise, reducing the cost of petrol and diesel by 26.3 cents a litre for three months.
The heavy road user charge will also be reduced to zero for the same period, taking pressure off truck drivers and transport costs.
Since the fuel price is set by market forces (rather than a cost plus model), and the law doesn’t prevent price gouging in energy (those laws only apply to supermarkets) we’ll likely see a drop (or at least a pause in the increases) when it’s first introduced, but then the fuel companies will slowly wind it back up till they are pocketing the excise change.
So no - there’s no framework forcing the saving to be passed on to motorists, and in the medium term it will go to fuel companies, funded by taxpayers.
While it’d be a massive fucking bureaucratic nightmare - the Govt should probably opt to refund the fuel excise levy on a monthly/quarterly basis through the ATO & financial institutions.
While it won’t do anything to curb panic-demand, it would at least provide an avenue for directly reducing end-user fuel costs in a noticeable way.