We spend $70 per week on petrol on average, and about $3,650 a year.
Last week another jump saw unleaded fuel rise an average 3.4 cents a litre to 152 cents - the highest for ten months.
So do motorists at least get the full measure?More stories from Today Tonight
Malcolm Bartlett of the National Measurement Institute says that by law we must get five litres if we pay for five.
We tested petrol pumps around Melbourne, Sydney and Brisbane to find out how much they actually delivered - filling five litres exactly on the pump - with regular unleaded and E10.
Each sample - every tiny drop - was meticulously dispensed into a glass beaker and verified to be exactly five litres by the National Measurement Institute.
90 per cent of our samples ended up being 50 to 100mls under the five litres.
Bartlett was surprised at our results as the National Measurement Institute tests fuel pumps regularly, unannounced.
"If you have a shortfall like that over a year, I agree it can be significant and that is what we're there for, to test the pumps to ensure that they are correct at all times," he said.