Methodology
The data
Every number on this site comes from official, publicly available government data. We don't make anything up and we don't guess. When we derive a metric (like roadside risk or warranty cliff), we explain exactly how.
DVSA anonymised MOT data
58 million individual test results and 109 million failure items from the 2024 test year. Make, model, registration year, mileage, pass/fail, and specific failure reasons. No registration numbers or personal information. Source.
DfT vehicle licensing statistics
Quarterly counts of licensed and SORN vehicles by make, model, and fuel type (VEH0120), plus new registrations per quarter (VEH0160). We combine these to calculate fleet growth, scrappage rates, and how many of each model remain on UK roads.
MOT test class data
DVSA test class IDs let us categorise vehicles: class 4 (cars), class 1+2 (motorcycles), class 5 (buses), class 7 (vans). This powers the category filters across the site.
All data is published under the Open Government Licence v3.0. Crown copyright.
How we count test results
Every MOT test in the DVSA data has one of five outcomes:
We also distinguish between normal tests (NT) and retests (RT). When a vehicle fails its MOT, the owner gets it repaired and brings it back for a retest. Our pass rates include both normal tests and retests because both are real tests on real vehicles, and excluding retests would artificially inflate pass rates.
On this site, “pass rate” means P as a percentage of P + PRS + F. We count PRS as a fail. The car had a testable defect when it arrived — the fact it was fixed at the station doesn't change that. If you're assessing build quality or comparing models, what matters is whether the car had a problem, not whether the garage had the right bulb in stock.
Some other sites count PRS as a pass, which inflates their pass rates. Neither approach is wrong — they answer different questions. Ours answers: “what percentage of these cars arrived at the MOT station with no defects?”
Aborted and abandoned tests are excluded from all calculations.
Worked example: Lexus UX
19,028 tests in 2024 (all test types)
If you counted PRS as a pass, you'd get 96.7%. The difference is small for the Lexus UX (2.1pp) but for models with higher PRS rates the gap widens. The methodology matters. We show you ours.
What MOT pass rate tells you
- How often a model has testable defects (brakes, lights, suspension, tyres, emissions, steering, bodywork corrosion, exhaust, seatbelts)
- Which specific components fail most often for each model
- How pass rates change with vehicle age
- Comparative defect rates between similar models
If you're buying a used car and one model consistently fails for suspension while another doesn't, that's useful; suspension repairs cost real money.
What MOT pass rate does NOT tell you
- Overall reliability: the MOT doesn't test engine internals, gearbox, electrics, air conditioning, infotainment, or most things that cause breakdowns
- Running costs: a car can pass its MOT and still be expensive to maintain
- Build quality: rattles, squeaks, and interior wear aren't MOT items
- How a specific car will perform: these are averages across thousands of vehicles of different ages and conditions
What skews the numbers
- Owner demographics: luxury cars score higher partly because owners invest more in maintenance, not necessarily because the cars are better built
- Pre-MOT checks: some owners get defects fixed before the test, which inflates the pass rate
- Age mix: a model that's only been on sale for 5 years will naturally score higher than one with 20 years of older examples in the fleet
- Variant grouping: the same model name can cover very different cars across generations
What we derive from the raw data
Beyond pass rates, we calculate several metrics that aren't in the raw data:
Roadside risk
We classify each failure item as “roadside” (could strand you — fractured springs, engine faults, exhaust failure), “safety” (car drives but is dangerous — worn brakes, steering play, tyre cord damage), or “MOT-only” (fails the test but the car is fine — lights, wipers, emissions). The percentage breakdown tells you what kind of trouble a model typically gets into.
Warranty cliff
Using year-by-year pass rates, we identify the age at which a model's failure rate spikes — typically between 3 and 7 years old, when manufacturer warranties expire. A 2020-registered car tested in 2024 is 3 years old; a 2016 registration is 7 years. We require 200+ tests per year to include a data point.
Mileage-normalised failure rate
Raw pass rates can be misleading. A car averaging 150,000 miles that passes 82% of the time is more impressive than one averaging 15,000 miles that passes 90%. To account for this, we calculate failures per 10,000 miles for every model with sufficient mileage data.
The formula: ((100 - passRate) / 100) / medianMileage × 10,000. We use the median mileage at test (the 50th percentile from all tests of that model) rather than the mean, which is less affected by outliers.
This metric reshuffles the rankings significantly. The Toyota Prius (82.4% raw, looks average) climbs to 9th best in the country because its 150,347 median miles means each failure represents far more driving. The London TX4 taxi (67.9% raw, looks terrible) climbs 553 places because at 187,154 median miles those cabs are the hardest-worked vehicles on UK roads and barely fail per mile driven. Conversely, low-mileage cars like the BMW Z4 (83.4% raw at just 17,429 miles) drop sharply when mileage is accounted for.
Limitations: median mileage is an approximation. It does not account for driving conditions (urban vs motorway), maintenance habits, or whether the car accumulates miles steadily or in bursts. Two cars with the same median mileage may have very different usage patterns. We show both the raw pass rate and the mileage-adjusted figure on model pages so you can draw your own conclusions. See our analysis of the most misleading MOT pass rates for a deeper look at what mileage normalisation reveals.
Estimated repair cost
We assign typical UK garage costs to each failure type (e.g. brake pads £150/axle, springs £250, bulbs £15) and weight them by how often each failure occurs for that model. This gives an average repair bill per failed MOT — not a quote, but a ballpark.
How we process the data
We run the raw DVSA CSV files through a multi-pass Python pipeline that:
- Reads all 58 million test results, computing pass rates, mileage averages, and age distributions per model, model-year, make, and fuel type
- Processes 100+ million failure items, matching each to its test to build per-model and per-model-year failure breakdowns
- Outputs JSON data files that are statically built into this website
If you have questions about our methodology, get in touch at hello@motdata.uk.
These are statistics, not predictions
A model with a 90% pass rate doesn't mean your car has a 90% chance of passing. Your vehicle's condition depends on its maintenance history, how it's been driven, mileage, and previous repairs. These numbers show patterns across thousands of vehicles. useful context for buying decisions, but never a substitute for inspecting the specific car.
Thresholds
- Model pages: minimum 1,000 tests
- Year breakdowns: minimum 100 tests per year
- League tables and rankings: minimum 10,000 tests
- Manufacturer rankings: minimum 50,000 tests
- Motorcycles are excluded from car rankings
Data licence and attribution
The DVSA anonymised MOT data is published under the Open Government Licence v3.0, which permits copying, publishing, distributing, and commercial use of the data, provided the source is acknowledged.
This site contains public sector information licensed under the Open Government Licence v3.0. Source: Driver and Vehicle Standards Agency (DVSA).
How we choose our partners
Some pages contain links to third-party services (tyre retailers, garages, insurance providers, breakdown cover, and extended warranties. We earn a commission if you click through and make a purchase. This costs you nothing extra.
We're selective about who we work with:
Trustpilot 4★ or above
Every partner must have a Trustpilot rating of 4 stars or higher with meaningful review volume. We check ratings before listing and remove partners if scores drop.
FCA registration where required
Insurance and finance partners are checked against the FCA register. We record registration numbers and verify they're authorised for the products they offer.
Complaint pattern analysis
We search for recurring complaint themes: rejected claims, misleading quotes, delivery failures. A high headline rating with poor claims experience doesn't pass our checks.
Free options always shown first
Every page with affiliate links also includes free government tools: the DVSA MOT history check, DVLA vehicle enquiry, and our own free data. We earn nothing from these.
Links are contextual, not blanket
We only show tyre links when the data shows tyres are a common failure for that model. Breakdown cover only appears when the roadside risk score is genuinely high. If the data doesn't support the link, it doesn't appear.
Full details in our affiliate disclosure.
What we don't do
- ✗We don't collect personal data: no forms, no email harvesting, no phone numbers
- ✗We don't sell leads to garages, insurers, or car dealers
- ✗We don't alter data or rankings to benefit affiliate partners
- ✗We don't hide free government tools to push commercial alternatives
- ✗We don't run PPC, voucher codes, or cashback schemes
Disclaimer
This website is an independent publication. It is not affiliated with, endorsed by, or connected to the DVSA, DVLA, or any vehicle manufacturer, brand, or company mentioned on this site. All manufacturer and model names are used solely to identify the vehicles in the DVSA dataset and are the trademarks of their respective owners.
The statistics presented are derived from government open data and are provided for informational purposes only. They are not vehicle safety advice, mechanical assessments, or recommendations to buy or avoid any vehicle. A model's MOT pass rate is a statistical summary of test outcomes across thousands of vehicles of different ages, mileages, and maintenance histories. It tells you nothing about the condition of any individual car.
Always check an individual vehicle's full MOT history on the DVSA's free tool, consider a professional pre-purchase inspection, and make your own assessment before buying a used vehicle. See our terms of use for full liability information.