The ACCC's Weekly Fuel Spotlight Switches Off Just as Prices Climb

Every Friday since 13 March, a dense PDF has landed on the competition watchdog's website telling Australians exactly what was happening between the oil tanker and the bowser. There have been 28 of them so far. And unless the federal government signs off on another extension in the next eight days, the weekly series ends with September.

The timing is hard to ignore. Last Friday's report showed average unleaded across the five biggest cities jumped 14.3 cents a litre in a single week, to 224.2c on 16 September. Diesel climbed 14.2c to 267.9c. Petrolmate's own numbers show prices have kept rising since.

Here's what's actually ending

The ACCC doesn't monitor fuel prices out of curiosity. It does it because the government directs it to, under the Competition and Consumer Act. The current direction was issued in December 2025 and runs for five years from 1 January 2026, with a detailed report every three months.

Then late February happened. Conflict escalated between the United States, Israel and Iran on 28 February, the ACCC switched to weekly reporting in March, and an amendment published on 1 May formally required weekly reports until 30 September 2026. That's the date to circle. The monitoring itself continues. What stops is the weekly public scorecard, with the ACCC dropping back to its quarterly rhythm.

To put this in perspective, a quarterly report covers roughly 13 weeks in one go. This year we've had a price shock, an excise cut, a staged excise return and a fresh oil spike, all inside six months. A quarterly timetable would have explained it all well after motorists had paid.

What 28 Fridays taught us

The peak came early. On 31 March the five city average for unleaded sat at around 257c, roughly 86c above where it was on 20 February. Diesel was worse, up around 146c to roughly 322c.

The excise experiment passed the test. The government cut excise by 32c a litre from 1 April, partly restored it on 1 July and fully restored it to 53.7c on 3 August. The ACCC's verdict in its latest report is that "overall, fuel businesses appeared to pass on the recent excise changes in their prices in an appropriate manner." That's regulator speak for: on average, nobody pocketed the tax cut.

The price cycle went missing. This is my favourite. For years Sydney, Melbourne, Brisbane and Adelaide ran on sawtooth cycles, with prices creeping down for weeks before leaping 20c or more almost overnight. The ACCC's 2025 figures put a typical cycle at about five weeks in Sydney, six in Melbourne, six and a half in Brisbane and two and a half in Adelaide. Since the conflict began, the ACCC says, those cycles have "mostly not occurred."

The capitals converged as a result. On 20 February, Brisbane drivers were paying 188.8c on average while Adelaide paid 161.3c, a 27.5c gap largely down to where each city sat in its cycle. By 16 September those four capitals were within 6.5c of each other.

Of the big five, only Perth kept its rhythm. Its weekly cycle, cheap on Tuesday and dear on Wednesday, survived the whole saga. On Tuesday 15 September the Perth average was 211.5c. A day later it was 230.0c.

Petrolmate's own daily data tells the same story. Over the past month the Western Australia median for unleaded jumped every single Wednesday, by between 8c and 13c each time, while the eastern state medians climbed in a smooth, almost straight line. No sawtooth anywhere.

The ruler got bendy. The ACCC's main yardstick for retail margins is the gap between terminal gate prices (the wholesale price companies post publicly) and the pump price. Back in March the Australian Institute of Petroleum said its members had stopped spot sales to prioritise regular customers, and the ACCC has since acknowledged that fewer deals are happening at or near those posted prices. In a nutshell, the margin ruler has been less reliable than usual.

Going back a few decades

Here's the fascinating backstory. The modern era of formal petrol monitoring dates to December 2007, when the government issued a monitoring direction off the back of the ACCC's inquiry into unleaded prices. The Rudd government then tried to go further with a national version of WA's FuelWatch, which makes servos lock in tomorrow's price a day ahead. The bill died in the Senate in November 2008 on a 34 to 34 vote, with Nick Xenophon famously likening it to one of those plastic dogs that nod their heads on the dashboard.

Compared to other countries, Australia's approach is a patchwork. Germany has required servos to report every price change to a federal transparency office within five minutes since 2013, and that data flows straight into consumer apps. Most Australian states now run mandatory price reporting schemes that do a similar job. What they don't do is explain *why* prices moved. That's been the ACCC's weekly job.

The practical upshot for your wallet

So what changes when the weekly lights dim? Three things are worth keeping in mind.

First, the pipeline. The ACCC says pump prices in the big cities typically lag wholesale by one to two weeks, because a servo's price tends to move when its tanks are refilled. Wholesale petrol rose about 14c in the week to 16 September alone. That's a big part of why the median unleaded price in NSW has gone from 204.9c on 1 September to 239.9c today in Petrolmate's data. Victoria went from 203.9c to 235.9c over the same stretch.

Second, the turnaround. Brent crude slipped back to around US$100 a barrel on 21 September after four straight losing sessions as diplomatic efforts picked up. If that holds, wholesale prices should follow, and pump prices should start easing a week or two later. Economists have a name for the pattern motorists dread, "rockets and feathers": prices shoot up quickly and drift down slowly. For six months a weekly public report has made that harder to get away with. From October, the next detailed check lands in three months.

Third, stop timing and start choosing. With no cycle in the eastern capitals, there's no magic cheap day to wait for. The saving is in picking the right servo. Across NSW in Petrolmate's latest data, the cheapest tenth of servos were at 229.9c or less for unleaded, while the dearest tenth were at 248.9c or more. That's 19c a litre, or about $9.50 on a 50 litre tank. In Queensland the same gap was 24c.

In Perth, Tuesday is still the day, and even on the Wednesday price jump of 16 September the ACCC counted 32 Perth servos selling unleaded under 210c. Our best time to fill up guide has the detail.

The bigger picture

The real story is that weekly monitoring was always an emergency measure, and the emergency hasn't neatly wrapped up. The ACCC's investigation into how Ampol, BP, Mobil and Viva Energy supplied diesel to regional independents, launched in March, is still open, and the ACCC stresses it hasn't formed a view. Canberra was the dearest capital for both petrol and diesel in the latest report.

And if the eastern price cycles quietly return once the spotlight fades? That would tell us something too. The government has extended the weekly reports once already. Whether it does so again is the thing to watch this week.

What to remember

The fuel industry rarely makes headlines until prices spike. This time the headlines are here, but the weekly scrutiny is about to go quiet. Keep an eye on this space.