Methodology & Sources
Last updated: October 26, 2026
Chassisworth reports are AI-assisted research, checked against cited sources. This page explains what we use, how we turn it into a value, and what a report can't tell you.
What we start from
Your order: the year, make and model, the VIN or chassis number, any engine stamp pad and trim or cowl tag numbers you type in, photos, the asking price and location, the listing link or pasted ad text, and the seller's claims. When something important is missing, such as stamp pad or trim tag photos, we build from what was submitted and list the gaps in the report.
Sources we use
- Decode tables and marque references. VINs, cowl and trim tags, castings and date codes are decoded from sourced lookup tables or cited marque references, never from memory. For 1981 and newer cars with a 17-character VIN, we validate the check digit, decode with NHTSA vPIC and check NHTSA recalls.
- Auction results. Live searches every time, never prices from memory: CLASSIC.COM, Hagerty Valuation Tools, Mecum, Barrett-Jackson, Bring a Trailer, RM Sotheby's, Bonhams, Broad Arrow and Gooding, plus aggregate sales data where available.
- Registries, dealer listings and forums, weighted below primary records.
- The listing and your photos, reviewed for consistency with the numbers and the seller's claims.
When sources disagree we rank them: factory record, then auction catalog, then registry, then dealer listing, then forum. Every comp and figure gets a link so you can check it. Bring a Trailer pages can't be read automatically, so we ask for pasted text.
Confirmed, Claimed, Unknown
Every key fact is tagged. Confirmed: documented or decoded from evidence. Claimed: the seller or listing says so, but it isn't verified. Unknown: not enough information, and the report names the specific check that would settle it.
How comps are normalized
Auction houses publish prices differently: some show the hammer price, some include the buyer's premium. We convert each comp to what the buyer actually paid (all-in), using that venue's own current fee schedule, re-checked for each report. For example, Mecum prices are shown as hammer, so we add its buyer's premium; Bring a Trailer prices are hammer plus a 5% buyer fee with a cap; Barrett-Jackson and the major traditional houses generally publish prices that already include the premium. If we can't tell which basis a price uses, the comp is marked not normalized and left out of the value. Fair market value is based on all-in figures only, from recent comparable sales with dates and condition context.
Buyer and seller versions
The research, comps and fair market value are the same whichever side you're on. Buyer versions add an offer band and walk-away triggers. Seller versions leave out the offer band and negotiation points so they can be shared with buyers, and they keep every red flag and gap.
How gaps are disclosed
When we can't verify something, we say so in the report instead of smoothing it over: missing photos, no listing, no auction history found for the VIN, or a comp whose price basis couldn't be confirmed. If there's no listing or price, the listing review and asking-versus-market comparison are skipped and the report says so. A review pass checks that each claim traces back to a source.
Limits
- A report is not an appraisal, a mechanical or physical inspection, a title search or a guarantee of authenticity. It can't be used for insurance, lending, legal or tax purposes.
- We work from documents, data, photos and what you and the seller provide. We don't see the car. A VIN that decodes correctly can still be on a different or altered car.
- AI tools can misread or make mistakes, which is why sources are cited for you to check.
- Market data is as of the report date, and comps for rare cars can be thin.
- For modern cars, we recommend a Carfax or AutoCheck report for title and accident history.
Have a qualified inspector look at any car in person before you buy. Questions: info@chassisworth.com. See also our sample report and Disclaimer.