2017 Smart Forfour — MOT failures & pass rate
27,402 MOT tests on the 2017 Smart Forfour are in this dataset, and 86.1% of them passed. That is 2.2 percentage points worse than city cars of a similar age, which fail at 11.7%. Failures cluster in tyres, visibility and lighting & signalling.
What the MOT record shows
No single area dominates — tyres (6.6%) and visibility (5.6%) 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 catalyst emissions — wipers alone was recorded 1,250 times.
Mileage is the strongest signal on the record: 10.0% of 0-30k cars fail, rising to 25.0% once past 120-150k — 2.5× the risk.
Tyres is the most common advisory, noted on 26.2% of tests — work that passed today but is likely due soon.
The trend is worsening — 10.9% of tests failed in 2021 against 16.5% in 2025, the usual pattern as a fleet ages.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Tyres | 6.6% | 1,802 |
| 2 | Visibility | 5.6% | 1,524 |
| 3 | Lighting & signalling | 3.8% | 1,037 |
| 4 | Brakes | 2.5% | 683 |
| 5 | Emissions & environmental | 2.4% | 647 |
| 6 | Suspension | 2.4% | 644 |
Most common specific failures
The exact components most often recorded as failures — more specific than the categories above.
| # | Failure item | Times recorded |
|---|---|---|
| 1 | Wipers | 1,250 |
| 2 | Tread depth | 1,090 |
| 3 | Catalyst emissions | 565 |
| 4 | Headlamp aim | 540 |
| 5 | Washers | 538 |
| 6 | Brake pads | 457 |
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 | 26.2% | 7,168 |
| 2 | Brakes | 16.0% | 4,388 |
| 3 | Other defects | 5.4% | 1,480 |
| 4 | Suspension | 3.2% | 889 |
| 5 | Visibility | 3.2% | 878 |
| 6 | Lighting & signalling | 1.4% | 387 |
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 | 12,958 | 10.0% |
| 30-60k | 11,750 | 16.0% |
| 60-90k | 2,348 | 22.4% |
| 90-120k | 281 | 27.4% |
| 120-150k | 48 | 25.0% |
Failure rate by age
By fuel type
| Fuel | Tests | Fail rate |
|---|---|---|
| Petrol | 27,055 | 13.9% |
| Electric | 347 | 15.0% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 5,389 | 10.9% |
| 2022 | 5,430 | 12.5% |
| 2023 | 5,518 | 13.7% |
| 2024 | 5,491 | 15.6% |
| 2025 | 5,574 | 16.5% |
What to check before buying a 2017 Forfour
The failure pattern for this year is specific enough to inspect against: tyres accounted for 6.6% of tests. Start there.
- Tyres (6.6% 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 (5.6% 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 (3.8% 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 2017 Smart Forfours pass their MOT?
86.1% of the 27,402 2017 Smart Forfour MOT tests in this dataset passed — a 13.9% fail rate.
What is the most common MOT failure on a 2017 Smart Forfour?
Tyres, recorded in 6.6% of tests, followed by visibility (5.6%).
Does the 2017 Forfour get worse with mileage?
Its MOT fail rate rises from 10.0% in the 0-30k band to 25.0% in the 120-150k band.
Methodology & source. Based on 27,402 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.