At a glance
How 2,767 first tests went in 2025.
- Passed first time
- 71 in every 100
- Did not pass first time
- 29 in every 100801 failed first-attempt tests
- The typical car
- 19 yearsabout 88,000 miles
- First tests counted
- 2,767
What failed most often
- Petrol engine warning light12 in every 100 failed tests
- Rigid brake pipes (rear)8 in every 100 failed tests
- Headlight aim8 in every 100 failed tests
How we count this. Data: UK MOT open data, 2025. Only Class 4 cars on their first MOT of the year are counted. A car that fails and is fixed at the test station still counts as a fail in the first-attempt rate. These are raw results, not adjusted for age, mileage, or peer mix. The MOT does not test engine or gearbox internals.
These are patterns across 2006 BMW Z4 vehicles in 2025, not a prediction that any one car will have them. Faults are grouped by part of the car. A wear pattern follows age and use more than the way the car was built. They come from MOT defect codes, not manufacturer bulletins, recalls or a diagnosis of any one car.
Body and structure
One fault: fuel cap, 3.9 times as often as on similar cars.
Figures below are measured across the 800 of 801 failed first attempts (99.9%) that recorded an odometer reading in 2025. Mileage is needed to compare like with like.
We only list faults with at least 20 failures and a rate of about 2.0 times that of similar cars, which keeps one-off results out of the list.
Fuel cap
What it means
A missing or ineffective fuel filler cap is Major, as is a plain fuel system leak, while a fuel system leaking excessively or a risk of fire has its own, separate wording. A fuel tank with a hole, or a split filler neck, from which fuel can leak must be failed for leaking even if the hole or split is above the fuel line.
Data: UK MOT open data, 2025. Compared with cars of the same age and mileage.
Brakes
Three faults. The strongest is the flexible brake hoses (front): 3.3 times as often as on similar cars.
Flexible brake hoses (front)
What it means
Testers reject a flexible brake hose for being excessively damaged or chafed only if it is severe enough to expose the reinforcement. Slight damage, chafing or twisting is graded Minor. A leak is graded Dangerous on a hydraulic braking system and Major on an air system, and a hose damaged and likely to fail is also Dangerous.
Also noted as an advisory
Testers also noted it as an advisory, worn but not yet failing, on 75 first tests, 3.4 times as often as on similar cars.
Rigid brake pipes (rear)
What it means
Chafing, corrosion or damage to a rigid brake pipe justifies rejection once its wall thickness is reduced by a set amount, although DVSA accepts this is not easy to determine. If a tester is not sure, the benefit of the doubt applies. A leaking pipe or connection is graded Dangerous on a hydraulic system and Major on an air system.
Also noted as an advisory
Testers also noted it as an advisory, worn but not yet failing, on 150 first tests, 2.2 times as often as on similar cars.
Rigid brake pipes (front)
What it means
Chafing, corrosion or damage to a rigid brake pipe justifies rejection once its wall thickness is reduced by a set amount, although DVSA accepts this is not easy to determine. If a tester is not sure, the benefit of the doubt applies. A leaking pipe or connection is graded Dangerous on a hydraulic system and Major on an air system.
Also noted as an advisory
Testers also noted it as an advisory, worn but not yet failing, on 103 first tests, 2.3 times as often as on similar cars.
Data: UK MOT open data, 2025. Compared with cars of the same age and mileage. Advisories count notes recorded on failed first tests only.
Lamps and electrical
One fault: horn, 2.3 times as often as on similar cars.
Horn
What it means
A horn that does not work, or is likely to be confused with an emergency vehicle siren, is graded Major. Gongs, bells, sirens and anything with more than one tone, which includes a horn that alternates between its notes, are not allowed, except a gong, bell or siren on vehicles first used before a set date. Sound defects are Minor for named cases such as a bell or harsh sound, and Major under a general row.
Data: UK MOT open data, 2025. Compared with cars of the same age and mileage.
Tyres
One wear pattern: tyre tread depth (rear), 2.2 times as often as on similar cars.
Tyre tread depth (rear)
What it means
Only primary grooves count when tread depth is assessed: those holding the wear indicators, or cut as deep as those when new. Shallower secondary grooves are ignored. Tread depth below the minimum for the vehicle is Dangerous, and so is a pattern not visible over the whole tread, but that second row applies only to vehicles that need the lower minimum.
Data: UK MOT open data, 2025. Compared with cars of the same age and mileage.
Suspension
One fault: shock absorbers (front), 2.1 times as often as on similar cars.
Shock absorbers (front)
What it means
Slight seepage that leaves a film of fluid on a shock absorber does not fail it. Severe leakage, or damage so that it does not function, is Major. A shock absorber missing or likely to become detached is graded Dangerous, though a missing one is only rejected if shock absorbers were fitted as standard.
Data: UK MOT open data, 2025. Compared with cars of the same age and mileage.
Noise, emissions and leaks
One fault: petrol engine warning light, 2.0 times as often as on similar cars.
Petrol engine warning light
What it means
The malfunction indicator lamp (MIL) on a petrol engine is a Major failure when it is illuminated indicating a malfunction. The detail line DVSA gives for the same row also names an inoperative lamp. The test covers only certain petrol vehicles, depending on their age, size and fuel type.
Data: UK MOT open data, 2025. Compared with cars of the same age and mileage.
Advisories
Other things testers noted as worn or close to failing, more often than on similar cars.
An advisory is a note from the tester about something that has not failed yet. It is an early warning, not a fail. Advisories for the faults above are shown with those faults.
Suspension arm ball joint (front)
Data: UK MOT open data, 2025. Counts cover advisories recorded on failed first tests only, compared with cars of the same age and mileage.
MOT pass rates
How first tests ended, and how the pass rates are counted.
- Passed first time
- 71in every 100
- Passed on the first test.
- Fixed at the station
- 5in every 100
- Failed, then fixed at the test station the same day.
- Failed
- 24in every 100
- Did not pass, and were not fixed at the test station.
First-attempt pass 71.1% of 2,767 first tests (2025): only cars that passed first time count. Official-style pass 75.8%: cars fixed at the test station also count as a pass. The 5 fixed and the 24 not fixed make the 29 in every 100 that did not pass first time.
Same model, other years
Passed first time in every 100, all tested in 2025.
Newer cars are younger, so look for a jump rather than the climb. A year earlier (2024), when these cars were a year younger, 69 in every 100 passed first time.
| Year | Passed first time | First tests |
|---|---|---|
| 2003 | 69 in every 100 | 2,277 |
| 2004 | 69 in every 100 | 2,759 |
| 2005 | 65 in every 100 | 1,835 |
| 2006 This car | 71 in every 100 | 2,767 |
| 2007 | 73 in every 100 | 2,971 |
| 2008 | 69 in every 100 | 1,674 |
| 2009 | 79 in every 100 | 2,358 |
| 2010 | 80 in every 100 | 1,890 |
| 2011 | 81 in every 100 | 1,876 |
| 2012 | 80 in every 100 | 1,769 |
| 2013 | 80 in every 100 | 1,515 |
| 2014 | 82 in every 100 | 1,839 |
| 2015 | 82 in every 100 | 1,530 |
| 2016 | 82 in every 100 | 1,179 |
If you are buying one
What this year's MOT record means for the decision in front of you.
Mileage matters most on a 2006 BMW Z4.
Of 2006 BMW Z4 vehicles with under 60,000 miles, 84 in every 100 passed their 2025 MOT first time. With 116,000 miles or more, 60 in every 100 did.
What to check at your mileage
How often each fault turned up on a failed first test, by the car's mileage. Read it as: what is likely to need looking at on a car like the one in front of you.
| Under 60,000 | 79,000–96,000 | 116,000 and over | |
|---|---|---|---|
| Petrol engine warning light | 1.1 | 2.2 | 7.0 |
| Rigid brake pipes (rear) | 0.4 | 2.7 | 3.8 |
| Headlight aim | 1.1 | 2.2 | 3.6 |
| Suspension arm pins and bushes (front) | 0.9 | 3.3 | 2.0 |
| Suspension arm ball joint (front) | 0.4 | 1.6 | 3.8 |
Faults per 100 first tests, by the car's mileage at the test.
When a car fails
of failed cars had one item to fix.
of failed cars had three or more items to fix.
of all first tests had a defect the tester marked dangerous (unsafe to drive away).
Every figure here is a first-attempt MOT rate from DVSA open data for this model line, for cars of this model year tested in 2025. Each mileage band holds a fifth of the tests. MOTs do not test engine or gearbox internals, so this is a pre-purchase checklist, not a full reliability score.
FAQs
Short answers about how to read this model-year guide.
About this data
How this page is built and what it can (and can't) say.
These figures come from UK MOT open data for this model year. We surface common failure patterns against similar cars, not a full reliability score, and not a pass/fail verdict on any individual vehicle.
What we include
UK Class 4 cars only. Normal MOT tests (not retests); first test per vehicle per calendar year; results pass, PRS, or fail.
Same-day repairs
PRS means the car failed items that were fixed at the test station and then passed the same day. We count PRS as a first-attempt fail in headline rates so same-day repairs do not hide problems.
How we compare
We compare this model year with other Class 4 cars of similar age and mileage in the same test year. This model family is left out of the peer group so the car is not measured against itself.
What this does not cover
- MOTs do not cover engine internals, gearboxes, or many electronics; this is not a full reliability score.
- Common faults come from MOT defect stats, not manufacturer TSBs or recalls.
- Age and mileage matching reduces, but does not remove, differences in how cars were used and maintained.
- If the data for a car is too thin to say anything useful, we say so rather than guess.
Contains public sector information licensed under the Open Government Licence v3.0.
Check any vehicle’s MOT history
Full MOT history, mileage records, and reliability insights for any UK vehicle.
Run a free check