2018 Mercedes-Benz GLC — MOT failures & pass rate
Across 107,567 MOT tests, the 2018 Mercedes-Benz GLC recorded a 90.5% pass rate. Mid-size SUVs of a similar age fail at 10.2%, so the 2018 GLC sits squarely on the average. Failures cluster in tyres, suspension and brakes.
What the MOT record shows
No single area dominates — tyres (4.8%) and suspension (2.3%) are close, so failures are spread across several systems rather than one weak point.
At component level the recurring items are ball joint, tread depth and brake pads — ball joint alone was recorded 2,595 times.
Mileage is the strongest signal on the record: 6.4% of 0-30k cars fail, rising to 19.8% once past 150k — 3.1× the risk.
Split by fuel, diesel examples fail 1.7pp more often than petrol ones (9.9% vs 8.2%) — worth weighing if you have a choice.
Advisories point at the next bill rather than this one: tyres was flagged on 21.3% of tests without failing them.
The trend is worsening — 7.1% of tests failed in 2021 against 12.5% in 2025, the usual pattern as a fleet ages.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Tyres | 4.8% | 5,119 |
| 2 | Suspension | 2.3% | 2,489 |
| 3 | Brakes | 1.5% | 1,618 |
| 4 | Visibility | 1.1% | 1,165 |
| 5 | Emissions & environmental | 1.1% | 1,129 |
| 6 | Lighting & signalling | 0.9% | 1,022 |
Most common specific failures
The exact components most often recorded as failures — more specific than the categories above.
| # | Failure item | Times recorded |
|---|---|---|
| 1 | Ball joint | 2,595 |
| 2 | Tread depth | 2,096 |
| 3 | Brake pads | 1,684 |
| 4 | Malfunction indicator lamp | 1,096 |
| 5 | Headlamp aim | 1,081 |
| 6 | Joints | 821 |
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 | 21.3% | 22,927 |
| 2 | Brakes | 11.4% | 12,242 |
| 3 | Other defects | 6.7% | 7,210 |
| 4 | Suspension | 5.6% | 5,995 |
| 5 | Visibility | 3.2% | 3,395 |
| 6 | Body, structure & corrosion | 0.5% | 498 |
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 | 33,499 | 6.4% |
| 30-60k | 53,712 | 9.8% |
| 60-90k | 17,130 | 13.5% |
| 90-120k | 2,693 | 15.5% |
| 120-150k | 412 | 17.5% |
| 150k+ | 116 | 19.8% |
Failure rate by age
By fuel type
| Fuel | Tests | Fail rate |
|---|---|---|
| Diesel | 82,633 | 9.9% |
| Petrol | 24,934 | 8.2% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 22,345 | 7.1% |
| 2022 | 21,582 | 7.4% |
| 2023 | 21,253 | 9.4% |
| 2024 | 21,192 | 11.3% |
| 2025 | 21,195 | 12.5% |
What to check before buying a 2018 GLC
On a 2018 GLC, tyres is what the MOT record says goes wrong most — it appeared in 4.8% of tests. Check these areas before you commit.
- Tyres (4.8% 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.
- Suspension (2.3% of tests): Worn drop links, bushes, springs or shocks — listen for knocks over bumps and check for uneven tyre wear. Typical repair: £150–£450 per corner.
- Brakes (1.5% 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 Mercedes-Benz GLCs pass their MOT?
90.5% of the 107,567 2018 Mercedes-Benz GLC MOT tests in this dataset passed — a 9.5% fail rate.
What is the most common MOT failure on a 2018 Mercedes-Benz GLC?
Tyres, recorded in 4.8% of tests, followed by suspension (2.3%).
Does the 2018 GLC get worse with mileage?
Its MOT fail rate rises from 6.4% in the 0-30k band to 19.8% in the 150k+ band.
Methodology & source. Based on 107,567 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.