2004 MG ZR — MOT failures & pass rate
5,157 MOT tests on the 2004 MG ZR are in this dataset, and 75.0% of them passed. That is 3.0 percentage points better than small family cars of a similar age, which fail at 28.0%. Failures cluster in lighting & signalling, body, structure & corrosion and brakes.
What the MOT record shows
One area stands out: lighting & signalling, recorded in 15.1% of tests against 10.4% for the next-worst category.
At component level the recurring items are joints, headlamp aim and catalyst emissions — joints alone was recorded 377 times.
Condition tracks the odometer closely. Failures run at 12.2% in the 0-30k band and 28.1% in the 150k+ band, a 15.9-point spread — more than double.
Tyres is the most common advisory, noted on 23.0% of tests — work that passed today but is likely due soon.
The trend is improving — the fail rate fell from 26.3% in 2021 to 22.8% in 2025, as the worst-kept examples leave the fleet.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Lighting & signalling | 15.1% | 779 |
| 2 | Body, structure & corrosion | 10.4% | 535 |
| 3 | Brakes | 7.8% | 404 |
| 4 | Emissions & environmental | 7.5% | 388 |
| 5 | Suspension | 6.2% | 321 |
| 6 | Visibility | 4.7% | 242 |
Most common specific failures
The exact components most often recorded as failures — more specific than the categories above.
| # | Failure item | Times recorded |
|---|---|---|
| 1 | Joints | 377 |
| 2 | Headlamp aim | 355 |
| 3 | Catalyst emissions | 331 |
| 4 | Component mounting prescribed areas | 287 |
| 5 | Headlamp | 219 |
| 6 | Position lamp | 218 |
Top advisory categories
Advisories aren't failures, but they flag work likely needed soon — useful when budgeting.
| # | Category | % of tests with advisory | Tests |
|---|---|---|---|
| 1 | Tyres | 23.0% | 1,188 |
| 2 | Brakes | 20.9% | 1,077 |
| 3 | Suspension | 20.6% | 1,065 |
| 4 | Body, structure & corrosion | 19.7% | 1,018 |
| 5 | Lighting & signalling | 15.0% | 772 |
| 6 | Steering | 13.0% | 671 |
Failure rate by mileage
Higher-mileage cars tend to fail more — often the most useful guide to real condition.
| Mileage band | Tests | Fail rate |
|---|---|---|
| 0-30k | 196 | 12.2% |
| 30-60k | 1,084 | 22.4% |
| 60-90k | 1,867 | 25.5% |
| 90-120k | 1,340 | 27.2% |
| 120-150k | 506 | 27.3% |
| 150k+ | 153 | 28.1% |
Failure rate by age
By fuel type
| Fuel | Tests | Fail rate |
|---|---|---|
| Petrol | 4,670 | 25.3% |
| Diesel | 487 | 22.6% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 1,468 | 26.3% |
| 2022 | 1,180 | 24.1% |
| 2023 | 1,029 | 25.7% |
| 2024 | 814 | 25.2% |
| 2025 | 666 | 22.8% |
What to check before buying a 2004 ZR
The failure pattern for this year is specific enough to inspect against: lighting & signalling accounted for 15.1% of tests. Start there.
- Lighting & signalling (15.1% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Body, structure & corrosion (10.4% of tests): The one to take seriously on older cars — corrosion to structural areas can be costly and is an MOT failure. Typical repair: £200–£1,500+.
- Brakes (7.8% of tests): Pads/discs are routine wear; binding, imbalance or corroded pipes are more serious — test for pulling under braking. Typical repair: £100–£350 per axle.
Repair costs are rough UK ballpark ranges to set expectations, not quotes — actual prices vary widely by car, parts and garage.
Frequently asked questions
How many 2004 MG ZRs pass their MOT?
75.0% of the 5,157 2004 MG ZR MOT tests in this dataset passed — a 25.1% fail rate.
What is the most common MOT failure on a 2004 MG ZR?
Lighting & signalling, recorded in 15.1% of tests, followed by body, structure & corrosion (10.4%).
Does the 2004 ZR get worse with mileage?
Its MOT fail rate rises from 12.2% in the 0-30k band to 28.1% in the 150k+ band.
Methodology & source. Based on 5,157 MOT tests. Dataset: DVSA MOT testing data (2021,2022,2023,2024,2025). Data last updated 2026-07-27. Figures reflect MOT-testable defects only — read the methodology for how these are calculated and what they don't measure.