2018 Smart Forfour — MOT failures & pass rate
21,308 MOT tests on the 2018 Smart Forfour are in this dataset, and 89.0% of them passed. Against city cars of a similar age (9.7% fail rate), the 2018 Forfour comes out 1.3pp worse. Failures cluster in visibility, tyres and lighting & signalling.
What the MOT record shows
No single area dominates — visibility (5.8%) and tyres (5.4%) are close, so failures are spread across several systems rather than one weak point.
At component level the recurring items are wipers, tread depth and washers — wipers alone was recorded 1,072 times.
A 90-120k example is materially riskier than a 0-30k one: 24.1% versus 8.4%.
Fuel type barely separates them — electric fails 9.7% of the time against 11.1% for petrol.
Advisories point at the next bill rather than this one: tyres was flagged on 22.8% of tests without failing them.
The trend is worsening — 8.1% of tests failed in 2021 against 13.6% in 2025, the usual pattern as a fleet ages.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Visibility | 5.8% | 1,243 |
| 2 | Tyres | 5.4% | 1,159 |
| 3 | Lighting & signalling | 2.8% | 595 |
| 4 | Brakes | 2.0% | 426 |
| 5 | Suspension | 1.4% | 291 |
| 6 | Emissions & environmental | 1.2% | 259 |
Most common specific failures
The exact components most often recorded as failures — more specific than the categories above.
| # | Failure item | Times recorded |
|---|---|---|
| 1 | Wipers | 1,072 |
| 2 | Tread depth | 625 |
| 3 | Washers | 394 |
| 4 | Headlamp aim | 393 |
| 5 | Brake pads | 294 |
| 6 | Catalyst emissions | 231 |
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 | 22.8% | 4,864 |
| 2 | Brakes | 13.9% | 2,956 |
| 3 | Other defects | 5.1% | 1,095 |
| 4 | Visibility | 3.0% | 639 |
| 5 | Suspension | 2.0% | 428 |
| 6 | Lighting & signalling | 1.3% | 268 |
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 | 13,851 | 8.4% |
| 30-60k | 6,486 | 15.3% |
| 60-90k | 831 | 20.0% |
| 90-120k | 116 | 24.1% |
Failure rate by age
By fuel type
| Fuel | Tests | Fail rate |
|---|---|---|
| Petrol | 20,428 | 11.1% |
| Electric | 880 | 9.7% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 4,173 | 8.1% |
| 2022 | 4,271 | 10.0% |
| 2023 | 4,305 | 10.9% |
| 2024 | 4,257 | 12.5% |
| 2025 | 4,302 | 13.6% |
What to check before buying a 2018 Forfour
On a 2018 Forfour, visibility is what the MOT record says goes wrong most — it appeared in 5.8% of tests. Check these areas before you commit.
- Visibility (5.8% 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.
- Tyres (5.4% 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 (2.8% 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 Smart Forfours pass their MOT?
89.0% of the 21,308 2018 Smart Forfour MOT tests in this dataset passed — a 11.0% fail rate.
What is the most common MOT failure on a 2018 Smart Forfour?
Visibility, recorded in 5.8% of tests, followed by tyres (5.4%).
Does the 2018 Forfour get worse with mileage?
Its MOT fail rate rises from 8.4% in the 0-30k band to 24.1% in the 90-120k band.
Methodology & source. Based on 21,308 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.