1,642 tests in 2025
Mercedes-Benz R reliability and MOT pass rate
77.6% passed first time. The 22.4% fail rate is 0.2 points better than the all-car average, on a median example 15 years old with 122,948 miles.
MOT pass rates / Mercedes-Benz
Pass rate
77.6%
22.6% of all cars failed; 22.4% of these did.
Fixed on the day
5.4%
Passed after a defect was put right during the visit.
Median at test
122,948 mi
15 years old.
Fail rate by age
| Age at test | Tests | Fail rate |
|---|---|---|
| 3-5 years | 0 | — |
| 6-9 years | 0 | — |
| 10-13 years | 383 | 21.7% |
| 14+ years | 1,259 | 22.6% |
What the R fails on
Share of failed tests with at least one fail item in each DVSA inspection section. A test can fail in several sections at once.
- Brakes64 dangerous49%
- Lamps, reflectors and electrical equipment1 dangerous35.4%
- Body, chassis, structure25.9%
- Noise, emissions and leaks1 dangerous19.9%
- Tyres61 dangerous19.9%
- Suspension6 dangerous17.2%
- Seat belts and supplementary restraint systems8.2%
- Visibility7.1%
Is the R getting worse?
The fail rate fell 2.6 points to 22.3% from 2022 to 2025 while the median one tested aged 1 year. Ageing alone would predict about 1.6 points, so it is holding up better than the fleet average for its age.
| Year | Tests | Median age | Fail rate | All cars | |
|---|---|---|---|---|---|
| 2022 | 2,701 | 14 | 24.9% | 22.5% | |
| 2023 | 2,447 | 14 | 23.5% | 22.8% | |
| 2024 | 1,868 | 15 | 25.3% | 23.2% | |
| 2025 | 1,631 | 15 | 22.3% | 22.6% |
Fail rate is first attempts at class 4 tests. Median age is the age of a typical R at its test that year, and it is the number to watch: across the whole fleet each extra year of age adds roughly 1.9 points to the fail rate, so a model whose age and fail rate rise together is simply getting older.
The exact defects that fail it
Every failure item DVSA recorded against a R in 2025, counted by how many tests each one appeared on.
- 1Joints: constant velocity boot split or insecure, no longer prevents the ingress of dirt72 tests
- 2Rbt (sp): efficiency below requirements54 tests
- 3Position lamp: not working49 tests
- 4Rigid brake pipes: excessively corroded38 tests
- 5Malfunction indicator lamp: inoperative or indicates a malfunction34 tests
- 6Decelerometer (sp): efficiency below requirements27 tests
- 7Condition: has a cut in excess of the requirements deep enough to reach the ply or cords22 tests
- 8Condition: has ply or cords exposed21 tests
What wears out first
Advisories are the tester flagging wear that is still legal. A typical R collects 2.81 of them per test, and these are the ones that come up most. Treat it as the running-repairs list for the next year or two.
- 1Engine oil leaks: leaking excessively from engine379 tests
- 2Rigid brake pipes: excessively corroded301 tests
- 3Tread depth: tread depth below requirements of 1.6mm276 tests
- 4Pins and bushes: pin or bush excessively worn128 tests
- 5Brake discs: in such a condition that it is seriously weakened112 tests
- 6Shock absorbers: has a serious fluid leak103 tests
- 7Brake pads: less than 1.5 mm thick95 tests
- 8Condition: has a tear, caused by separation or partial failure of its structure87 tests
Questions
What is the Mercedes-Benz R MOT pass rate?
77.6% of the 1,642 Mercedes-Benz R first-attempt MOTs in 2025 passed. The fail rate of 22.4% compares with 22.6% across all cars. A further 5.4% passed after a defect was fixed during the test visit.
What does a Mercedes-Benz R usually fail on?
The single most common failure is "Joints: constant velocity boot split or insecure, no longer prevents the ingress of dirt", recorded on 72 failed tests, followed by "Rbt (sp): efficiency below requirements" and "Position lamp: not working". By section, brakes appears in 49% of failures, lamps, reflectors and electrical equipment appears in 35.4% of failures, body, chassis, structure appears in 25.9% of failures.
Does age change the odds?
Sharply. At 3 to 5 years old the fail rate was n/a%; at 14+ years it was 22.6%. The median Mercedes-Benz R tested in 2025 was 15 years old with 122,948 miles.
Is the Mercedes-Benz R getting less reliable?
The fail rate fell 2.6 points to 22.3% from 2022 to 2025 while the median one tested aged 1 year. Ageing alone would predict about 1.6 points, so it is holding up better than the fleet average for its age.
First-attempt class 4 tests, 2025, from DVSA’s anonymised MOT data (OGL v3, retrieved 2026-09-12). DVSA records newer cars trim by trim; this page adds every R trim together. Year-on-year figures come from the same DVSA extracts for 2026 and earlier years. Full method on the pass rates hub.
Other Mercedes-Benz models
Checking a particular R?
The odds above are the model. The car in front of you has its own record: every test, every advisory, the mileage at each one.
Due a test? Find an approved MOT station near you.