How we know what we say we know.

Where the evidence comes from.

Completed sales from public auctions and dealer sales across the US collector-car market, matched to each car's exact model, generation and variant. Every comparable shows where and when it sold, so you can see the evidence behind a value. Coverage is growing model by model; where a model's sales are still being gathered, Stable says so.

How the evidence becomes a value.

Comparable sales are weighted by how closely they match the car and how recently they sold. Adjustments for mileage, gearbox, modifications, condition and factory options are estimated from the market's own sales, not set by hand. Stable Value is in early access: the model is still learning, and values can move as more sales are added.

Why every value has a range.

Every value comes with a range: the middle of the comparable evidence, from the 20th to the 80th percentile once each sale is adjusted to the car. When evidence is thin or comparables disagree, the range widens and the confidence level falls. We would rather be honest than precise.

What Declared, Documented and Verified mean.

Declared facts are entered by the owner. Documented facts have evidence in the Vault, such as a title, invoice or window sticker. Verified facts will be those a Stable specialist has checked against the car and its records, dated; verification is being introduced, so today's facts are Declared or Documented.

Values are not for sale.

Stable Value is calculated the same way whether or not a car is offered on Stable, and no seller, dealer or advertiser can pay to change it.

Your collection is yours.

Values, costs and documents are private by default. We do not sell data about you or your cars. Vehicle details help improve the model only without your name or contact details, and aggregated market statistics never identify a car or an owner.

Every change is on the record.

Methodology changes are published here with a date and an explanation. Individual values show their history, so you can see how and when they moved.