2018 Porsche Cayman — MOT failures & pass rate
The 2018 Porsche Cayman passed 94.9% of its 6,530 recorded MOT tests. Against coupes & convertibles of a similar age (9.0% fail rate), the 2018 Cayman comes out 3.9pp better. Failures cluster in tyres, visibility and lighting & signalling.
What the MOT record shows
No single area dominates — tyres (3.5%) and visibility (0.9%) are close, so failures are spread across several systems rather than one weak point.
At component level the recurring items are tread depth, registration plates and washers — tread depth alone was recorded 164 times.
Condition tracks the odometer closely. Failures run at 4.4% in the 0-30k band and 10.2% in the 60-90k band, a 5.8-point spread — more than double.
Tyres is the most common advisory, noted on 15.5% of tests — work that passed today but is likely due soon.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Tyres | 3.5% | 226 |
| 2 | Visibility | 0.9% | 60 |
| 3 | Lighting & signalling | 0.8% | 54 |
| 4 | Other defects | 0.6% | 39 |
| 5 | Brakes | 0.3% | 18 |
| 6 | Emissions & environmental | 0.3% | 17 |
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 | 164 |
| 2 | Registration plates | 62 |
| 3 | Washers | 53 |
| 4 | Headlamp aim | 47 |
| 5 | Headlamp cleaning device | 15 |
| 6 | Wipers | 11 |
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 | 15.5% | 1,015 |
| 2 | Brakes | 3.2% | 207 |
| 3 | Other defects | 2.4% | 158 |
| 4 | Visibility | 1.7% | 110 |
| 5 | Suspension | 1.1% | 74 |
| 6 | Emissions & environmental | 0.5% | 34 |
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 | 4,702 | 4.4% |
| 30-60k | 1,707 | 6.7% |
| 60-90k | 108 | 10.2% |
Failure rate by age
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 1,466 | 6.0% |
| 2022 | 1,336 | 3.9% |
| 2023 | 1,266 | 4.8% |
| 2024 | 1,226 | 5.5% |
| 2025 | 1,236 | 5.3% |
What to check before buying a 2018 Cayman
The failure pattern for this year is specific enough to inspect against: tyres accounted for 3.5% of tests. Start there.
- Tyres (3.5% 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.
- Visibility (0.9% of tests): Wipers, washers, mirrors and screen damage — usually inexpensive, but check for chips in the driver's line of sight. Typical repair: £15–£150.
- Lighting & signalling (0.8% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
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 Porsche Caymans pass their MOT?
94.9% of the 6,530 2018 Porsche Cayman MOT tests in this dataset passed — a 5.1% fail rate.
What is the most common MOT failure on a 2018 Porsche Cayman?
Tyres, recorded in 3.5% of tests, followed by visibility (0.9%).
Does the 2018 Cayman get worse with mileage?
Its MOT fail rate rises from 4.4% in the 0-30k band to 10.2% in the 60-90k band.
Methodology & source. Based on 6,530 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.