But GST is a cost to the final consumer so from a dollar point of view the consumer is still going to being paying for the cost of it regardless if it is in the way of a tax on one item as is the case with fuel or a tax across all items as would be the case of an increase in GST
Assuming all cost savings are passed on, the cost of goods would reduce by the amount the producers save in cheaper fuel. But the cost to the consumer of the goods would rise to cover the revenue lost by removing the fuel tax.
You end up back where you started, save $20 on filling your tank and pay $20 a week in additional GST on every thing you purchase
