Know what to check before you buy a modified car
ModCheck turns a registration and what the seller tells you into a screening report: known weak points for the model, what the modifications mean, official records where available, and exactly what to ask and inspect.
Look up the car
Official DVLA and MOT records, where those services are connected.
Add what the seller says
Model, mileage, service history and any modifications, with how well each is documented.
Get a screening report
Weak points to verify, what’s unknown, and a checklist of questions, documents and inspections.
Every fact is labelled by where it came from
- Official recordReturned by a connected official service.
- Seller-reportedWhat you entered from the advert or seller. Not verified.
- Model profilePublished reports about the model, with sources. Not confirmed on any one car.
- UnknownMissing, not connected or can’t be assessed yet.
Tell us about the car
Choose the model and enter what the seller has told you. Or load a fictional sample car to see a full report.
Compare two or three cars
Pick two or three from fictional sample cars or reports you’ve saved. This compares screening results, not mechanical condition.
Checking for the ModCheck server…
How ModCheck works today
A rules engine, a small library of model profiles and, where they’re connected, official DVLA and DVSA MOT records looked up by registration. Lookups go through ModCheck’s own server, so no keys or third-party scripts reach your browser.
The screening score
The score adds up flags from four separate areas so the same concern isn’t counted twice: usage (age and mileage together), maintenance evidence, modifications, and known weak points for the model. Their maximums (25, 25, 30 and 20) add up to 100. Each point is labelled as coming from something you reported, from missing information, or from the model profile. It’s a way to prioritise checks, not a prediction that anything will fail.
Evidence statuses
Each weak point is labelled. Manufacturer-acknowledged means the maker publicly acknowledged it or ran a recall or service programme. Specialist-reported means a named specialist or specialist publication describes it, which makes it a known possible failure, not a measured rate. Owner reports only and Needs review items are shown so you can check them but don’t count towards the score. Track-use issues aren’t scored because how a car was used is rarely known, and modification-related issues are left to the modifications area.
Most profiles were desk-researched in October and November 2026 from the sources shown in each report, mainly UK specialists, UK motoring publications and recall records. That research hasn’t been checked by a specialist. Each report shows its profile’s research date. The Civic Type R FK8, E46 M3, M135i, Cayman S, WRX STI and GR Yaris profiles haven’t been researched yet, so their weak points are shown for checking but don’t add to the score.
What still needs calibration
The area maximums, item points, severity weights, the half weight for conditional issues, the multipliers for documented modifications, the 90,000-mile priority trigger, the mileage and age thresholds and the verdict bands are all design choices. None has been calibrated against real inspection outcomes. The score is a way to prioritise checks. It isn’t a probability of failure or a prediction of a car’s remaining life.
What a report is, and isn’t
A ModCheck report is a preliminary screen of the details entered. It isn’t an inspection, diagnosis, guarantee or valuation. It can’t tell whether any listed issue is present on a particular car, so every weak point is shown as unknown on that car. The suggested next step defers to any car-specific items that need resolving before a score-based recommendation is given.
Modifications
Modification points measure how much there is to verify, not evidence that a change causes faults. The weights are design choices. The one with an external basis is emissions equipment, where the MOT inspection manual applies.
Modifications are weighted by what they affect and how well they’re documented. A documented remap counts for less than an undocumented one, and wheels, brakes and cat-back exhausts add nothing on their own. Suspected modifications are treated as missing information.
Evidence labels
Every report shows where its information came from. Official record means a connected DVLA or DVSA service returned it for that registration. Seller-reported means you entered it from the advert or the seller, and it isn’t verified. Model profile means published reports about the model, not confirmed on any one car. Unknown means it’s missing, not connected or can’t be assessed yet. Sample reports are marked as fictional. Potential severity describes how serious an issue would be if present, which is separate from how much evidence there is for it.
What ModCheck does
- Validated inputs, checked against each model’s years and gearboxes
- Reports that echo exactly what was entered, and flag when the form changes
- Screening score with a factor-by-factor breakdown
- Model weak points with symptoms, checks, evidence status and cited sources
- Modification analysis by evidence status
- Official records and an MOT mileage cross-check, when those services are connected
- Editable running-cost calculator showing its method
- Seller questions, inspection checklist, saved reports and comparison
Data sources
- Checking which services are connected…
Still to do
- Specialist review of the desk-researched profiles, and a database to maintain them
Privacy and your data
Without an account, saved reports stay in this browser only. With an account, ModCheck stores your email address, a secure hash of your password and the details of reports you save, so you can use them on other devices. Registration lookups are sent to the official services that are connected, and ModCheck doesn’t keep the registrations you look up in your account history. To avoid repeating lookups, the server holds each result in memory for up to six hours, then discards it. Some reports include partner links, for example to a history check; ModCheck may earn a commission from them and counts only that a link was clicked, not who clicked it. You can download everything stored about you, or delete your account and all saved reports, from the Account page. The full privacy policy has the details.
Privacy
Last updated 4 November 2026. This explains what ModCheck stores, why, and what you can do about it, in plain English.
Who runs ModCheck
ModCheck is run by Aidan Webb, who is responsible for your data under UK data protection law. Contact: hello@modcheck.co.uk.
What’s stored, and why
- Registration lookups. When you enter a registration, ModCheck’s server sends it to the official DVSA MOT history service (and the DVLA vehicle service once it’s connected). To avoid repeating lookups, the result is held in the server’s memory for up to six hours, then discarded. ModCheck records that a lookup happened and when, linked to your account if you’re signed in, so it can apply fair-use limits. It doesn’t keep the registrations you look up.
- Your account, if you make one. Your email address, a secure hash of your password (never the password itself), when you agreed to this policy, and the reports you choose to save. This lets you use saved reports on other devices.
- Mistakes you report. Your message, which part of the report it’s about and the car’s details from the report. Your email address and the registration are only included if you choose to add them.
- Visit counts. To see how many people use ModCheck and where they came from, each page load records the date, which page was shown, any tag in the link (such as
?ref=tiktok) and the website that linked to it. Visitors are counted using a scrambled code made from the visitor’s internet address and browser with a secret that changes every day and is never written to disk, so the code can’t be traced back to you or used to follow you from day to day. Your internet address itself isn’t stored, and no cookie is used for this. - Partner link clicks. Some reports link to partners, for example for a vehicle history check. ModCheck may earn a commission from these and records only which link was clicked and when, not who clicked it. Once you’re on a partner’s site, their own privacy policy applies.
- Security. To stop abuse, the server briefly keeps a count of recent requests from each internet address in memory. It isn’t stored.
The legal bases are: providing the service you asked for (lookups, your account and saved reports), and ModCheck’s legitimate interests in running, improving and protecting the service (mistake reports, visit counts, click counts and security).
Cookies and browser storage
ModCheck uses only what it needs to work, so there’s no cookie banner. A sign-in cookie keeps you signed in (up to 30 days), and during the beta an invite cookie remembers that you’ve entered the code (up to 90 days). Your browser also keeps your colour theme and, if you don’t have an account, your saved reports. Those stay on your device and never reach the server. There are no advertising or third-party tracking cookies.
Where it’s kept, and for how long
ModCheck’s server and database are hosted by Hetzner in Germany. Email to ModCheck is handled by Zoho, with data held in the UK. Account details and saved reports are kept until you delete them or your account. Lookup counts, visit counts, click counts and mistake reports are deleted after about 13 months. Mistake reports sent while you’re signed in are also deleted if you delete your account. Nightly backups of the database are kept on the server for 14 days, so deleted data disappears from them within two weeks.
Your rights
You can download everything stored about your account, or delete your account and all its saved reports, from the Account page. You can also ask to see, correct or delete your data, or object to how it’s used, by emailing hello@modcheck.co.uk. If you’re unhappy with the answer, you can complain to the Information Commissioner’s Office at ico.org.uk.
Changes
If this policy changes, the date at the top will change. Significant changes will be shown on the site.
Terms of use
Last updated 4 November 2026. By using ModCheck you agree to these terms. They’re short, and worth reading before you rely on a report.
What ModCheck is
ModCheck is a free tool that helps you decide what to check before buying a used car. Its reports are a preliminary screen of the details you enter, alongside official MOT records where available. A report isn’t a vehicle inspection, diagnosis, history check, guarantee, valuation or financial advice. ModCheck doesn’t know the condition of any car and can’t tell you whether a listed issue is present or has been fixed.
Accuracy
MOT records come from the DVSA and are shown as provided. ModCheck can’t guarantee they’re complete or correct. Model weak points are researched from published sources, may be incomplete, out of date or wrong for a particular car, and most haven’t yet been reviewed by a specialist. ModCheck is in beta, so features and results may change and the service may sometimes be unavailable.
Your decisions
Before buying, get an independent inspection by someone qualified and a full vehicle history check (for outstanding finance, write-offs and theft records, which MOT records don’t cover). Any decision to buy, and at what price, is yours.
Liability
ModCheck is provided free and as it is. As far as the law allows, ModCheck isn’t responsible for any loss arising from relying on a report, including the cost of buying or repairing a car. Nothing in these terms limits liability for death or personal injury caused by negligence, for fraud, or for anything else that can’t be limited by law, and your rights as a consumer aren’t affected.
Fair use
Use ModCheck for your own car research. Don’t use it to collect data in bulk, run automated lookups, get around its limits, interfere with the service, or for anything unlawful, including using registration lookups to track or harass anyone. ModCheck may limit or suspend access that breaks these terms.
Accounts
Keep your password private. You can delete your account at any time from the Account page.
Partner links
Some reports link to partners, such as vehicle history checks or inspections. ModCheck may earn a commission if you buy through them, at no extra cost to you. Partners provide their own services under their own terms.
Data sources
MOT history is provided by the Driver and Vehicle Standards Agency (DVSA). Contains public sector information licensed under the Open Government Licence v3.0. ModCheck isn’t affiliated with or endorsed by the DVSA or DVLA.
The law
These terms are governed by the law of England and Wales. If you live in Scotland or Northern Ireland, you can also bring claims in your local courts.