What Gas Costs
and Why
An independent guide to the price at the pumpData release · 30 September 2026

The evidence behind the price

South Australia: what changed?

Dated inputs, measured movements and the limits of each comparison.

Why prices changed

Gasoline / petrol

+0.112 AUD/L (+4.998%)

The gasoline price moved from 2.241 on 2026-09-20 to 2.353 on 2026-09-27. The chart reconciles the measured change using the site’s accounting model.

Contribution values
Estimated accounting contributions, AUD/L
ComponentChange
Crude benchmark movement-0.042
Exchange-rate movement+0.013
Refining & distribution residual+0.131
Taxes+0.010
Rounding / unallocated remainder+0.000

Left: decrease. Right: increase. Oil is valued at the earlier FX rate; currency movement uses the later oil price. The downstream residual includes unmeasured costs and timing, not just margins. Taxes can change with prices without a policy change. This is accounting, not proof of causation.

Diesel

+0.152 AUD/L (+5.531%)

The diesel price moved from 2.748 on 2026-09-20 to 2.900 on 2026-09-27. The chart reconciles the measured change using the site’s accounting model.

Contribution values
Estimated accounting contributions, AUD/L
ComponentChange
Crude benchmark movement-0.042
Exchange-rate movement+0.013
Refining & distribution residual+0.167
Taxes+0.014
Rounding / unallocated remainder+0.000

Left: decrease. Right: increase. Oil is valued at the earlier FX rate; currency movement uses the later oil price. The downstream residual includes unmeasured costs and timing, not just margins. Taxes can change with prices without a policy change. This is accounting, not proof of causation.

Reporting around these observation dates

Source headlines provide context. Their presence does not establish what caused the price movement.

No matching source reports are available for this observation interval.

Oil fell. Did the pump follow?

Gasoline / petrol

Does local crude movement line up more closely with pump changes in the same week or later? This compares weekly changes at delays of 0 to 8 weeks over up to five years, using the latest continuous publisher and currency segment.

Pump price and local-currency crude, indexed to 1002026-09-06 to 2026-09-27. Navy is pump price; teal is crude. A data table follows.03264961282026-09-062026-09-27Pump price (navy) · Crude in local currency (teal) · First paired date = 100
Relative movements, not a breakdown of pump costs. Crude is a proxy, not wholesale fuel.
Chart data and publishers (4 observations)
DatePump, AUD/LCrude proxy, local / LPublisher
2026-09-062.0470.893Australian Institute of Petroleum
2026-09-132.0851.035Australian Institute of Petroleum
2026-09-202.2411.057Australian Institute of Petroleum
2026-09-272.3531.028Australian Institute of Petroleum

3 compatible weekly changes; at least 52 are required for lag analysis.

At least 52 compatible weekly changes are needed; each correlation needs 12 pairs and variation in both series. Joins allow one day of reporting-date variation. Missing weeks are not filled. Each later pump change covers one week, not a cumulative response. Correlation does not measure a causal pass-through delay or prove that rises travel faster than falls. No forecast is implied. Benchmark and FX inputs are no more than 10 days old and never from a future date.

Diesel

Does local crude movement line up more closely with pump changes in the same week or later? This compares weekly changes at delays of 0 to 8 weeks over up to five years, using the latest continuous publisher and currency segment.

Pump price and local-currency crude, indexed to 1002026-09-06 to 2026-09-27. Navy is pump price; teal is crude. A data table follows.03264961282026-09-062026-09-27Pump price (navy) · Crude in local currency (teal) · First paired date = 100
Relative movements, not a breakdown of pump costs. Crude is a proxy, not wholesale fuel.
Chart data and publishers (4 observations)
DatePump, AUD/LCrude proxy, local / LPublisher
2026-09-062.5540.893Australian Institute of Petroleum
2026-09-132.5961.035Australian Institute of Petroleum
2026-09-202.7481.057Australian Institute of Petroleum
2026-09-272.9001.028Australian Institute of Petroleum

3 compatible weekly changes; at least 52 are required for lag analysis.

At least 52 compatible weekly changes are needed; each correlation needs 12 pairs and variation in both series. Joins allow one day of reporting-date variation. Missing weeks are not filled. Each later pump change covers one week, not a cumulative response. Correlation does not measure a causal pass-through delay or prove that rises travel faster than falls. No forecast is implied. Benchmark and FX inputs are no more than 10 days old and never from a future date.

Policy dates alongside prices

Gasoline / petrol
AUD per litre, with policy event dates2026-09-06 to 2026-09-27. Dashed lines mark verified policy events; they do not establish causation. A data table follows.0.000.641.271.912.542026-09-062026-09-27Australian Institute of Petroleum · AUD/L
No curated policy events fall within the displayed price history.
Chart data and publishers (4 observations)
DatePump, AUD/LPublisher
2026-09-062.047Australian Institute of Petroleum
2026-09-132.085Australian Institute of Petroleum
2026-09-202.241Australian Institute of Petroleum
2026-09-272.353Australian Institute of Petroleum

2022-03-30

Australian fuel excise temporarily halved

Temporary measure from 30 March through 28 September 2022. A numeric household estimate is withheld until the applicable before and after rates are recorded.

A monetary impact is not estimated from the available verified rates.

Australian Parliamentary Budget Office

2022-09-29

Australian temporary excise reduction ended

The temporary six-month reduction ended. Indexation means restoration should not be assumed to equal the original cut.

A monetary impact is not estimated from the available verified rates.

Australian Parliamentary Budget Office

Event coverage is selective. Source tax-rate snapshots are not automatically treated as legal changes. Upcoming recorded tax dates · All regional tax records

Diesel
AUD per litre, with policy event dates2026-09-06 to 2026-09-27. Dashed lines mark verified policy events; they do not establish causation. A data table follows.0.000.781.572.353.132026-09-062026-09-27Australian Institute of Petroleum · AUD/L
No curated policy events fall within the displayed price history.
Chart data and publishers (4 observations)
DatePump, AUD/LPublisher
2026-09-062.554Australian Institute of Petroleum
2026-09-132.596Australian Institute of Petroleum
2026-09-202.748Australian Institute of Petroleum
2026-09-272.900Australian Institute of Petroleum

2022-03-30

Australian fuel excise temporarily halved

Temporary measure from 30 March through 28 September 2022. A numeric household estimate is withheld until the applicable before and after rates are recorded.

A monetary impact is not estimated from the available verified rates.

Australian Parliamentary Budget Office

2022-09-29

Australian temporary excise reduction ended

The temporary six-month reduction ended. Indexation means restoration should not be assumed to equal the original cut.

A monetary impact is not estimated from the available verified rates.

Australian Parliamentary Budget Office

Event coverage is selective. Source tax-rate snapshots are not automatically treated as legal changes. Upcoming recorded tax dates · All regional tax records

Source receipts

Gasoline / petrol

Publisher: Australian Institute of Petroleum. Observation: 2026-09-27. Last successful publisher refresh: 2026-09-30 07:43:10 UTC. Observation ingestion: 2026-09-30 07:41:33 UTC.

Original value: 235.3 AUD cents/L. Display: 2.353000 AUD/L. Method: derived.

Crude input
Brent 114.89 USD/barrel, 2026-09-22
Display currency FX
USD_AUD 1.42243269, 2026-09-25
Source currency FX
USD_AUD 1.42243269, 2026-09-25
Reuse terms
AIP / MotorMouth. Attribute; review republication terms

Derived method: crude = USD/barrel / 158.987 * local currency/USD; yield factor 1.0; downstream = price - taxes - crude. Currency conversion uses display FX / source FX; US gallons convert at 3.785411784 L. Missing inputs are never zero. Benchmark availability alone does not imply a complete component breakdown. Full methodology.

Download receipts and calculation inputs · Historical observations

Publication and revision history (3 saved versions)

Tracking begins with this feature’s first export. A new observation is a publication; a changed value for the same observation date is a revision. This is our publication history, not a complete publisher revision archive. At most 30 versions per fuel are shown; the canonical database retains all recorded versions.

Recorded (UTC)ObservationPrice / LVersion
2026-09-30T07:44:54.787421Z2026-09-272.353000 AUD013ad2c3e02c
2026-09-24T13:02:09Z2026-09-202.241000 AUD1919f96decc1
2026-09-23T06:02:23Z2026-09-202.241000 AUD893c2b0d3e3c
Diesel

Publisher: Australian Institute of Petroleum. Observation: 2026-09-27. Last successful publisher refresh: 2026-09-30 07:43:10 UTC. Observation ingestion: 2026-09-30 07:42:44 UTC.

Original value: 290 AUD cents/L. Display: 2.900000 AUD/L. Method: derived.

Crude input
Brent 114.89 USD/barrel, 2026-09-22
Display currency FX
USD_AUD 1.42243269, 2026-09-25
Source currency FX
USD_AUD 1.42243269, 2026-09-25
Reuse terms
AIP / MotorMouth. Attribute; review republication terms

Derived method: crude = USD/barrel / 158.987 * local currency/USD; yield factor 1.0; downstream = price - taxes - crude. Currency conversion uses display FX / source FX; US gallons convert at 3.785411784 L. Missing inputs are never zero. Benchmark availability alone does not imply a complete component breakdown. Full methodology.

Download receipts and calculation inputs · Historical observations

Publication and revision history (3 saved versions)

Tracking begins with this feature’s first export. A new observation is a publication; a changed value for the same observation date is a revision. This is our publication history, not a complete publisher revision archive. At most 30 versions per fuel are shown; the canonical database retains all recorded versions.

Recorded (UTC)ObservationPrice / LVersion
2026-09-30T07:44:54.793266Z2026-09-272.900000 AUDc1baa35874ae
2026-09-24T13:02:09Z2026-09-202.748000 AUD73f2cd9c8cc3
2026-09-23T06:02:23Z2026-09-202.748000 AUD17fd34222c4c

South Australia price overview · Embed this region’s chart