Sydney drivers are being urged to stop filling up their cars with premium petrol and instead use cheaper fuel.
The NRMA is backing claims that in most cases the highly refined option is a waste of money.
A new report by FuelWatch shows the gap between regular unleaded and premium steadily climbing over the past decade.
The difference in the international price is about 2 cents a litre. Wholesale it’s about 8 cents a litre but at the pump 15.5 cents a litre.
According to David Atkin from the BMW Drivers Club, “That's a way of getting higher margin when they're getting a lower margin on low octane fuel.”
Most European cars need 95 or 98 octane so their drivers have no choice but to buy it.
The NRMA says the oil companies know it and demanding the competition watchdog investigate.
Peter Khoury from the NRMA says: “There's less reason to compete on the premium fuels and that's why we see these prices as high as they are.”
As the gap between the price of regular and premium grows it seems more and more drivers are paying it - sales of premium are on the rise and in New South Wales it even outsells E10.
But motoring groups say drivers using premium unnecessarily are wasting their money.
Khoury warns: “Don't fill up with this high grade fuel if you don't have to if it’s not in your owner’s manual because you're not getting the benefits you think you are.”
Many drivers disagree, telling 7News: “I have noticed quite a lot of extra mileage out of it”, and that it “just runs better.”
Regardless, they're urging all of us to fill up soon as the current discount cycle's about to end sending prices soaring 12 cents a litre.