Methodology
This page sets out where every figure in a CarWorthIt report comes from, whether it is measured or estimated, how often it updates, and what it cannot tell you. If you are a journalist or researcher checking a number we published, this is the page to read, and media@carworthit.com is the address to query it at.
Source for every field
“Measured” means the figure is a record someone filed. “Modelled” means it is calculated from comparable data. “Estimated” means it rests on national averages, and we say so wherever it appears.
| Field | Source | Type | Updates |
|---|---|---|---|
| Year, make, model, trim, body, engine, plant | NHTSA vPIC VIN decoder Decoded from the VIN itself. Some pre-2000 vehicles decode partially because manufacturers filed less detail. | Measured | Continuously, by NHTSA |
| Open safety recalls | NHTSA recalls database Recalls are matched by year, make and model, so a campaign limited to a narrow VIN range may show for a vehicle outside it. Always confirm with a dealer. | Measured | As manufacturers file campaigns |
| Crash-test ratings | NHTSA NCAP 5-star safety ratings Not every trim is tested. An untested variant shows no rating rather than an inherited one. | Measured | Annually, per model year |
| MPG and annual fuel cost | EPA fueleconomy.gov EPA test-cycle figures at 15,000 miles a year. Real-world economy varies with driving style, climate and condition. | Measured | Annually, per model year |
| Title brands, salvage, junk, flood, theft, odometer, auction records | A licensed commercial US vehicle-data provider Only ever shows what was actually reported to an insurer, body shop, police force or DMV. A privately repaired accident may never appear anywhere. | Measured, where reported | Per lookup, live |
| Market value | Commercial market-pricing feed built on dealer listing comparables A statistical estimate from comparable listings, not an appraisal. Condition, service history and local demand can move a real sale price either side of it. | Modelled | Per lookup, live |
| 5-year cost to own | EPA fuel data plus US national averages Only the fuel line is specific to your car. Insurance, maintenance, repairs, taxes and depreciation are national averages scaled by vehicle age, and are labelled as estimates in the report. | Estimated | Reviewed periodically |
What our data cannot tell you
Stating this plainly matters more than the features list. No vehicle history report in the United States, ours or anyone else's, can see the following:
- An accident that was never reported to an insurer, police force or body shop.
- Current mechanical condition, hidden rust, or the quality of past repair work.
- Whether outstanding recall work has actually been carried out.
- Wear that has not yet failed, which is what a pre-purchase inspection is for.
There is also no public US dataset of VIN-level title brands. Every commercial provider, including the household names, licenses this from the same small set of sources, which is why no report is exhaustive.
How we handle corrections
If a figure here or in one of our studies is wrong, we correct it on the page and say what changed, rather than deleting it. Email media@carworthit.com. We do not publish competitor prices, because they change without notice and a stale price is worse than none.
Who does the analysis
David Skillett, Founder and Analyst. David Skillett founded CarWorthIt after building CarCostCheck, a UK vehicle-data service that analyses more than 62 million government MOT test records. He works with public vehicle datasets from NHTSA, the EPA and the FBI, and writes CarWorthIt’s data studies and buying guides.