A few months ago I started building About This Car, a small UK vehicle lookup. You type in a registration, it pulls the public record for that car from several sources at once, merges what it finds, and writes a plain-English summary on top.

The AI summary is the visible part. The more useful lesson was how much information about a used car is already public and free, if you know where to look.

What a registration unlocks, for nothing

Every car registered in Great Britain has a DVLA record, and most of it is visible to anyone with the plate. Tax status, or whether the car has been declared SORN. The date the current V5C logbook was issued. Engine size, fuel type, colour (and whether the colour has changed), the CO2 figure that drives its tax band.

Then there's MOT history. Every car in England, Scotland and Wales over three years old needs an annual MOT, and the full test history since 2005 is free on GOV.UK: every pass, fail, advisory and recorded mileage. Northern Ireland runs its own separate scheme, so it isn't in that service.

Add the official DVSA recall checker and askMID (the Motor Insurance Database's public check) and you have four free, official sources that between them answer most of the questions a buyer should be asking before a viewing.

The patterns worth looking for

Put the DVLA record and MOT history side by side and certain warning signs stand out:

• Mileage that drops between tests, or flatlines for a suspiciously long stretch.
• The same advisory turning up year after year without ever being fixed.
• Gaps in the MOT record that line up with the car being SORN or untaxed.
• A fail followed by a very quick pass.
• A logbook issue date that's much more recent than the seller's story would suggest.

None of these prove anything on their own. Each one is a good question to ask before you hand over a deposit.

What isn't free (and why that matters)

Whether a car has been recorded as an insurance write-off (Category A, B, S or N) sits on a database called MIAFTR, and there's no free government route to it. Outstanding finance is the same. If you want those answers, you need a paid history check, and on any meaningful purchase it's money well spent.

I'd rather say that plainly than let a free tool imply it covers more than it does. About This Car shows the DVLA record, tax status and MOT status and expiry, with an AI summary on top. For the full test-by-test MOT history I point people to GOV.UK, because that's where it lives.

What building it actually involved

For anyone thinking of building something similar, a few things surprised me.

The official API isn't always open. DVLA has a proper Vehicle Enquiry Service API, but on 16 July 2026 it stopped accepting new key registrations during system upgrades. So the app reads the same free public enquiry service a person would use, through a headless browser. The adapter for the official API is already written and sits switched off, ready for the day a key arrives.

Plenty of sources don't want to be read by software. Several commercial check sites sit behind bot protection, and I excluded them rather than fight it. Others returned data inconsistently. The lesson was to treat every source as optional: run them all in parallel, take what each one gives, and record which source each field came from.

Serverless browsers have a cost. Running headless Chromium on a hobby hosting plan means the first lookup after a quiet spell takes around 30 seconds while the browser unpacks. Warm, it's under five. That trade-off is fine for a side project. It wouldn't be for a commercial one.

And the AI summary is only as good as the record underneath it. The model is very good at turning eighteen fields into two readable paragraphs. It has no way of knowing about a write-off that isn't in the data it was given, which is exactly why the copy around it has to be honest.

The takeaway

If you're buying a used car, the free checks take five minutes and need nothing but the registration. Do them before the viewing, not after you've fallen for the car.

If you'd like them in one place, About This Car is free to use at aboutthiscar.com, and the guides walk through each official check in more detail, including the ones I can't do for you.