2018 BMW 4 Series — MOT failures & pass rate
88,802 MOT tests on the 2018 BMW 4 Series are in this dataset, and 89.8% of them passed. That is 1.2 percentage points worse than coupes & convertibles of a similar age, which fail at 9.0%. Failures cluster in tyres, lighting & signalling and brakes.
What the MOT record shows
Tyres dominates the failure mix at 7.0% of all tests — 5.3 points clear of lighting & signalling, so it is the first thing to check.
At component level the recurring items are tread depth, headlamp aim and brake pads — tread depth alone was recorded 1,721 times.
Mileage is the strongest signal on the record: 7.5% of 0-30k cars fail, rising to 15.7% once past 150k — 2.1× the risk.
Fuel type barely separates them — petrol fails 9.8% of the time against 10.5% for diesel.
Advisories point at the next bill rather than this one: tyres was flagged on 19.9% of tests without failing them.
The trend is worsening — 9.2% of tests failed in 2021 against 11.6% in 2025, the usual pattern as a fleet ages.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Tyres | 7.0% | 6,203 |
| 2 | Lighting & signalling | 1.7% | 1,509 |
| 3 | Brakes | 1.4% | 1,232 |
| 4 | Visibility | 1.1% | 1,019 |
| 5 | Road wheels | 0.7% | 591 |
| 6 | Suspension | 0.5% | 463 |
Most common specific failures
The exact components most often recorded as failures — more specific than the categories above.
| # | Failure item | Times recorded |
|---|---|---|
| 1 | Tread depth | 1,721 |
| 2 | Headlamp aim | 1,121 |
| 3 | Brake pads | 1,057 |
| 4 | Washers | 709 |
| 5 | Registration plates | 565 |
| 6 | Wipers | 387 |
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 | 19.9% | 17,672 |
| 2 | Brakes | 11.3% | 10,019 |
| 3 | Other defects | 5.5% | 4,902 |
| 4 | Suspension | 2.8% | 2,439 |
| 5 | Visibility | 2.5% | 2,181 |
| 6 | Emissions & environmental | 1.0% | 912 |
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 | 30,054 | 7.5% |
| 30-60k | 41,980 | 10.7% |
| 60-90k | 13,685 | 13.6% |
| 90-120k | 2,582 | 14.4% |
| 120-150k | 414 | 14.2% |
| 150k+ | 83 | 15.7% |
Failure rate by age
By fuel type
| Fuel | Tests | Fail rate |
|---|---|---|
| Diesel | 45,886 | 10.5% |
| Petrol | 42,916 | 9.8% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 18,682 | 9.2% |
| 2022 | 17,879 | 8.6% |
| 2023 | 17,556 | 10.3% |
| 2024 | 17,387 | 11.4% |
| 2025 | 17,298 | 11.6% |
What to check before buying a 2018 4 Series
On a 2018 4 Series, tyres is what the MOT record says goes wrong most — it appeared in 7.0% of tests. Check these areas before you commit.
- Tyres (7.0% of tests): Usually a quick, known-cost fix, but check tread, age and uneven wear (which can hint at alignment or suspension issues). Typical repair: £50–£120 per tyre.
- Lighting & signalling (1.7% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Brakes (1.4% 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 2018 BMW 4 Seriess pass their MOT?
89.8% of the 88,802 2018 BMW 4 Series MOT tests in this dataset passed — a 10.2% fail rate.
What is the most common MOT failure on a 2018 BMW 4 Series?
Tyres, recorded in 7.0% of tests, followed by lighting & signalling (1.7%).
Does the 2018 4 Series get worse with mileage?
Its MOT fail rate rises from 7.5% in the 0-30k band to 15.7% in the 150k+ band.
Methodology & source. Based on 88,802 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.