The AUCN Risk Index: Australian Used Car Risk, Month by Month

Used-car risk is usually discussed as a fixed fact: "about one in ten cars has finance owing." In reality it moves. The AUCN Risk Index tracks those movements every month, using the outcomes of AUCN's own national vehicle checks.

The current reading

September 2026: 97.2 — down 2.6 points from August, and below the 2023 baseline for the first time since early 2025.

The index over the last twelve months

The pattern through 2026 is a clear turn: risk built through the first half of the year, peaked in May, and has come down sharply since — a fall of 19 points in four months.

What the index is made of

The weights reflect how often each flag changes the outcome of a purchase: finance owing and written-off history both routinely kill or reprice a deal, while a stolen record is rarer but absolute when it appears.

Each component is expressed as a share of vehicles checked in that month, and the weighted composite is divided by its own 2023 calendar-year value and multiplied by 100. That makes 2023 the reference point rather than an arbitrary number.

Annual readings

What actually moves the index

• Finance owing is the biggest lever (45%). It rises when more late-model and financed vehicles enter the used market and falls as those loans age out. It ran between 11.0% and 11.9% for most of 2025–26 before dropping to 10.1% in September 2026.
• Written-off history (40%) moves with weather and repair economics. Hail and flood events produce a wave of write-offs that reaches the resale market months later.
• Stolen records (15%) are small but sharp. At under 1% they barely move the composite month to month, but they matter disproportionately for motorcycles and for specific models.

What it means if you are buying or selling

• Buying: a falling index means the odds are improving, not that they are gone. At 97.2, roughly one in four vehicles still carries at least one risk flag — the check is still the cheapest part of the transaction.
• Selling: when the index is falling, buyers have more clean cars to choose from, so a documented, no-finance vehicle commands a bigger premium than usual.
• Dealers: the index is a stock-risk barometer. The 2026 peak coincided with the highest finance-owing rates in the series; anyone buying stock in that window should expect more payout letters and settlement delays.

How to cite it

AUCN Risk Index (September 2026), aucn.net.au — baseline: 2023 = 100.

The index is reviewed monthly and restated if the underlying check data changes. Full definitions are on the AUCN Data methodology page.

Related AUCN data

• Nearly 1 in 4 used cars carry a hidden risk flag
• Which brands still have finance owing
• Written-off rates vary by state

About this data: AUCN Data, percentage basis. The index is calculated from AUCN's national PPSR check outcomes, with each component expressed as a share of vehicles checked in the period and weighted 45/40/15 (finance owing / written-off / stolen). Baseline: 2023 calendar year = 100. Odometer anomalies are published separately because the reporting coverage of that field changed during 2026; including it would distort the series. Small-sample months (2021–22) are shown for context only.