How our price figures are made

ScanAuctions is car-sourcing software used by UK dealers: it scans dealer sale platforms (Motorway and CarWow) and public UK marketplace listings, and values each car against retail. Two datasets power the public figures on this site:

• Price observations (1,224,993 at the last snapshot) — individual asking/listed prices collected from public UK marketplace listings and dealer-platform listings, each with the car’s make, model, year, mileage, fuel and gearbox where available. This powers the price guides.
• Scan results (~99,000 dealer-platform listings) — cars our software scanned on Motorway and CarWow, pairing each listing’s asking or reserve price with its AutoTrader retail valuation at scan time. This powers the auction-vs-retail figures and our auction price study.

Most of our data never reaches a public page. Before a figure is published:

• Prices outside £1,000–£150,000 and registration years outside 2000–2026 are excluded as implausible.
• A model only gets a price guide with at least 1,000 observations and at least 8 registration years each backed by 50+ cars.
• Year rows need 50+ cars; mileage bands need 25+; auction sections need 200+ scanned listings for that model — below those floors, the section simply doesn’t render.
• “Cheapest seen” figures are suppressed when the lowest price is under 40% of that year’s average — those listings are usually accident-damaged or Cat-marked cars, and printing them as a market floor would mislead.
• Month-by-month trends only render once the series is long and stable enough to reflect the market rather than changes in what we scanned.

• Averages and medians are simple arithmetic over the observations that pass the gates, per model, per year, or per mileage band.
• The auction-to-retail gap is retail value minus platform asking price, per car. Percentage gaps are calculated per car and then averaged — cheaper cars carry proportionally larger gaps, so the average percentage is higher than dividing the average £ gap by the average retail value. Both are true; they answer different questions.
• The “value sweet spot” is the registration year with the largest one-year price drop among cars four or more years old. Drops that size usually sit where a model changed generation — the pages say so rather than implying the two years are the same car.
• Modelled margin deducts platform buyer fees (from published fee tables and real dealer invoices) and typical preparation costs from the gap. It is an estimate, and where it rounds to nothing on a model, the page says “close to zero”.

• These are asking prices, not sold prices. Final sale prices typically land at or near asking on competitive stock, but we don’t observe the hammer.
• Retail values are AutoTrader retail valuations at scan time, not what any individual car eventually sold for on a forecourt.
• Our sample is what we scan — dealer platforms and public UK listings. It is very large, but it is not a census of every UK car sale.
• Averages hide condition. No table can price a specific car’s history, bodywork or gearbox whine — that’s what a valuation and a cold-start test drive are for.

You’re welcome to cite any figure on this site with attribution to ScanAuctions and a link to the page it came from. Figures carry the date they were last updated; snapshots refresh monthly, so quote the dateline with the number. For custom cuts — by segment, region, model or time period — email info@scanauctions.com with your deadline; we answer journalist data requests quickly and for free.