Mercedes-Benz R-Class MOT pass rate & common failures
14,394 MOT tests on the Mercedes-Benz R-Class (2005–2017) give it a 79.6% pass rate. That is 6.1 percentage points better than MPVs of a similar age, which fail at 26.5%. Its most common failure areas are lighting & signalling, brakes and emissions & environmental.
Best and worst R-Class years
Ranked across R-Class years with at least 1,000 tests. Older cars fail more simply because they are older — compare years close together in age before drawing conclusions.
What the MOT record shows
Build year matters more than the headline suggests: 2012 cars pass 83.2% of the time while 2007 cars manage 77.1%, a 6.1-point spread.
No single area dominates — lighting & signalling (10.1%) and brakes (9.6%) are close, so failures are spread across several systems rather than one weak point.
At component level the recurring items are joints, position lamp and rigid brake pipes — joints alone was recorded 610 times.
A 150k+ example is materially riskier than a 0-30k one: 22.0% versus 12.0%.
Split by fuel, diesel examples fail 2.3pp more often than petrol ones (20.6% vs 18.3%) — worth weighing if you have a choice.
Advisories point at the next bill rather than this one: brakes was flagged on 30.5% of tests without failing them.
The trend is improving — the fail rate fell from 20.9% in 2021 to 19.1% in 2025, as the worst-kept examples leave the fleet.
How it compares
By model year
Every R-Class model year with a usable sample. Years with their own detailed report are linked.
| Year | Tests | Pass rate | Fail rate | Most common failure |
|---|---|---|---|---|
| 2006 | 2,304 | 79.0% | 21.0% | Lighting & signalling |
| 2007 | 2,545 | 77.1% | 22.9% | Lighting & signalling |
| 2008 | 2,001 | 78.5% | 21.5% | Brakes |
| 2009 | 1,286 | 77.9% | 22.1% | Lighting & signalling |
| 2010 | 1,428 | 79.7% | 20.3% | Lighting & signalling |
| 2011 | 2,214 | 80.6% | 19.4% | Brakes |
| 2012 | 1,672 | 83.2% | 16.8% | Brakes |
| 2013 | 909 | 83.3% | 16.7% | Lighting & signalling |
Most common failures (all years)
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Lighting & signalling | 10.1% | 1,458 |
| 2 | Brakes | 9.6% | 1,386 |
| 3 | Emissions & environmental | 4.5% | 655 |
| 4 | Body, structure & corrosion | 4.5% | 643 |
| 5 | Tyres | 4.2% | 609 |
| 6 | Suspension | 3.8% | 547 |
| 7 | Visibility | 2.1% | 295 |
| 8 | Seat belts & restraints | 1.6% | 224 |
Most common specific failures
The exact components most often recorded as failures — more specific than the categories above.
| # | Failure item | Times recorded |
|---|---|---|
| 1 | Joints | 610 |
| 2 | Position lamp | 590 |
| 3 | Rigid brake pipes | 551 |
| 4 | Headlamp aim | 441 |
| 5 | Rbt (sp) | 409 |
| 6 | Tread depth | 324 |
| 7 | Malfunction indicator lamp | 304 |
| 8 | Stop lamp | 299 |
Top advisory categories
Advisories aren't failures, but they flag work likely needed soon — useful when budgeting.
| # | Category | % of tests with advisory | Tests |
|---|---|---|---|
| 1 | Brakes | 30.5% | 4,389 |
| 2 | Tyres | 23.5% | 3,390 |
| 3 | Emissions & environmental | 22.7% | 3,262 |
| 4 | Suspension | 15.4% | 2,222 |
| 5 | Body, structure & corrosion | 13.7% | 1,978 |
| 6 | Other defects | 8.3% | 1,190 |
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 | 83 | 12.0% |
| 30-60k | 770 | 15.7% |
| 60-90k | 2,656 | 17.7% |
| 90-120k | 4,380 | 20.9% |
| 120-150k | 3,715 | 21.6% |
| 150k+ | 2,773 | 22.0% |
Failure rate by age
By fuel type
| Fuel | Tests | Fail rate |
|---|---|---|
| Diesel | 13,312 | 20.6% |
| Petrol | 1,082 | 18.3% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 3,653 | 20.9% |
| 2022 | 3,274 | 20.7% |
| 2023 | 2,927 | 19.8% |
| 2024 | 2,493 | 21.1% |
| 2025 | 2,047 | 19.1% |
What to check before buying a Mercedes-Benz R-Class
- Lighting & signalling (10.1% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Brakes (9.6% 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.
- Emissions & environmental (4.5% of tests): More common on older diesels (DPF/EGR) — can be expensive; check for warning lights and smoke. Typical repair: £100–£600.
Repair costs are rough UK ballpark ranges to set expectations, not quotes — actual prices vary widely by car, parts and garage.
Frequently asked questions
What is the MOT pass rate for the Mercedes-Benz R-Class?
79.6% of the 14,394 Mercedes-Benz R-Class MOT tests in this dataset passed, a 20.4% fail rate, across model years 2005–2017.
What does the Mercedes-Benz R-Class most often fail its MOT on?
Lighting & signalling, recorded in 10.1% of tests, then brakes (9.6%).
Which R-Class years are best and worst for MOT results?
2012 has the best pass rate at 83.2% and 2007 the weakest at 77.1%, from 1,672 and 2,545 tests respectively.
How much does mileage affect R-Class MOT results?
Fail rates run at 12.0% for cars in the 0-30k band and 22.0% for 150k+, a 10.0-point difference.
Is the petrol or diesel R-Class more reliable at MOT time?
On MOT-testable defects the petrol fails 18.3% of the time against 20.6% for the diesel. This covers testable items only, not engine or gearbox reliability.
Methodology & source. Based on 14,394 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.