Audi A4 vs Mercedes-Benz C-Class: which fails its MOT less?
Allowing for age, the Audi A4 and Mercedes-Benz C-Class fail their MOT about as often.
- of Audi A4 MOTs passed in 2024
- 76.8%of Audi A4 MOTs passed in 2024
Mercedes-Benz C-Class: 78.0%
Both fail less often than normal for their age.
Data: DVSA MOT results · 2024 · 609,708 tests
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Which fails less for its age?
Allowing for age, there is no practical difference (under 5 points apart): MOT Risk Index 87.4 for the Audi A4, 87.4 for the Mercedes-Benz C-Class (100 = normal for its age).
Both fail less often than normal for their age.
| Measure | Audi A4 | Mercedes-Benz C-Class | Years |
|---|---|---|---|
| Passed at the first attempt, % | 72.1 | 74.1 | 2024 |
| MOT Risk Index (100 = normal) | 87.4 | 87.4 | 2024 |
| 95% interval of the index | 86.9–88.0 | 86.9–87.9 | 2024 |
| Rank among 761 models (1 = fails least for its age) | 327 | 327 | 2024 |
| First tests | 244,118 | 365,590 | 2024 |
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After defects were fixed at the test centre
76.8% of Audi A4 tests and 78.0% of Mercedes-Benz C-Class tests passed, including defects fixed during the test. This is a different outcome from passing at the first attempt.
What explains the difference?
The clearest difference is suspension: against its own class and age, the Audi A4 runs −1.6 items per 100 tests and the Mercedes-Benz C-Class +2.6, so the Audi A4 has 4.1 fewer per 100 tests (95% interval 4.0 to 4.2).
Each model is compared with its own class and age; the fleets can differ in mileage and use.
More detail
Dangerous defects and advisory items
| Measure | Audi A4 | Mercedes-Benz C-Class |
|---|---|---|
| Dangerous defects per 100 tests | 12.0 | 11.7 |
| Advisory items per 100 tests | 135.2 | 117.1 |
Source: DVSA MOT bulk data, 2019–2024. A test can record several items. CSV
At what age does one of them fail more?
They change places at age 10: the difference is clear at 11 of 17 ages, and which fails less depends on the age of the car. Across the 4 yearly tests from age 4 to 7, the gaps add up to 2.2 extra failed tests per 100 for the Audi A4 (a sum of yearly rates, not the chance of one car failing).
| Age | Difference, pp | 95% interval | Reading |
|---|---|---|---|
| 3 | −0.2 | −0.6 to +0.2 | not distinguishable |
| 4 | −0.3 | −0.7 to +0.1 | not distinguishable |
| 5 | +0.0 | −0.4 to +0.5 | not distinguishable |
| 6 | +1.1 | +0.6 to +1.5 | Mercedes-Benz C-Class fails less |
| 7 | +1.4 | +0.9 to +1.8 | Mercedes-Benz C-Class fails less |
| 8 | +0.9 | +0.4 to +1.3 | Mercedes-Benz C-Class fails less |
| 9 | +0.0 | −0.5 to +0.5 | not distinguishable |
| 10 | −0.9 | −1.5 to −0.4 | Audi A4 fails less |
| 11 | −1.4 | −2.0 to −0.8 | Audi A4 fails less |
| 12 | −0.8 | −1.4 to −0.2 | Audi A4 fails less |
| 13 | −0.6 | −1.3 to +0.0 | not distinguishable |
| 14 | −1.3 | −1.9 to −0.6 | Audi A4 fails less |
| 15 | −1.3 | −2.0 to −0.6 | Audi A4 fails less |
| 16 | −2.0 | −2.7 to −1.2 | Audi A4 fails less |
| 17 | −2.0 | −2.8 to −1.1 | Audi A4 fails less |
| 18 | −1.5 | −2.5 to −0.6 | Audi A4 fails less |
| 19 | −0.5 | −1.6 to +0.7 | not distinguishable |
| Age band | Ages included | Audi A4, % | Mercedes-Benz C-Class, % | Difference, pp | 95% interval | Reading |
|---|---|---|---|---|---|---|
| 3–5 | 3–5 | 12.9 | 13.1 | −0.1 | −0.3 to +0.0 | not distinguishable |
| 6–10 | 6–10 | 22.1 | 21.4 | +0.8 | +0.6 to +0.9 | Mercedes-Benz C-Class fails less |
| 11+ | 11–20+ | 36.6 | 36.9 | −0.4 | −0.5 to −0.2 | Audi A4 fails less |
Source: DVSA MOT bulk data · Window: 2019–2024 · n = 3,579,864 (initial tests at shared ages) · Method: difference of two proportions per age, Bonferroni-corrected for 17 ages; age bands pool the published ages with an unadjusted 95% interval, and the same car can appear at more than one age, so that interval is somewhat narrow · Updated: 25 Sep 2026 · Release: dvsa-2024-v2 · CSV
Where do their MOT failures diverge?
The clearest difference is suspension: against its own class and age, the Audi A4 runs −1.6 items per 100 tests and the Mercedes-Benz C-Class +2.6, so the Audi A4 has 4.1 fewer per 100 tests (95% interval 4.0 to 4.2).
| Component group | Audi A4 vs its class | Mercedes-Benz C-Class vs its class | Gap, Audi A4 minus Mercedes-Benz C-Class | 95% interval | Reading |
|---|---|---|---|---|---|
| Suspension | −1.6 | +2.6 | −4.1 | −4.2 to −4.0 | Audi A4 fails less |
| Body, chassis, structure | +0.2 | −3.8 | +4.0 | +4.0 to +4.1 | Mercedes-Benz C-Class fails less |
| Brakes | −3.4 | −0.1 | −3.2 | −3.3 to −3.2 | Audi A4 fails less |
| Lamps, reflectors and electrical equipment | −5.4 | −6.9 | +1.5 | +1.5 to +1.6 | Mercedes-Benz C-Class fails less |
| Noise, emissions and leaks | −0.9 | −0.1 | −0.8 | −0.9 to −0.8 | Audi A4 fails less |
| Steering | −0.9 | −1.6 | +0.6 | +0.6 to +0.7 | Mercedes-Benz C-Class fails less |
Source: DVSA MOT bulk data · Window: 2019–2024 · n = 3,709,776 (initial tests) · Method: each model's failure items per 100 tests against the rate expected for its own class and age; Poisson interval; the age standard leaves the model out and is treated as fixed; items in the same test are treated as independent, so the interval is slightly narrow · Updated: 25 Sep 2026 · Release: dvsa-2024-v2 · CSV
If one fails, which is more likely to fail again?
A failure carries about the same extra risk of failing again on both: 10.0 percentage points on the Audi A4, 9.2 on the Mercedes-Benz C-Class.
| Measure | Audi A4 | Mercedes-Benz C-Class |
|---|---|---|
| After a failed test, % | 33.5 | 30.2 |
| After a passed test, % | 23.6 | 21.0 |
| Extra risk carried by a failure, pp | 10.0 | 9.2 |
Source: DVSA MOT bulk data · Window: 2019–2024 · n = 184,102 (tests after a fail) · Method: test chains of the same vehicles; cars sold or scrapped after a fail drop out · Updated: 25 Sep 2026 · Release: dvsa-2024-v2 · CSV
What do six years of MOTs show about the two?
The biggest gap in advisories turning into fails is body, chassis, structure: 15.1% on the Audi A4 against 6.2% on the Mercedes-Benz C-Class failed on the same item at the next MOT.
| Component | Audi A4 | Mercedes-Benz C-Class | Difference, pp |
|---|---|---|---|
| Body, chassis, structure | 15.1 | 6.2 | +9.0 |
| Suspension | 17.3 | 23.8 | −6.5 |
| Steering | 13.9 | 10.6 | +3.3 |
| Visibility | 11.4 | 9.3 | +2.1 |
| Seat belts and supplementary restraint systems | 3.9 | 5.3 | −1.3 |
| Brakes | 10.8 | 11.7 | −0.9 |
| Road wheels | 1.3 | 2.1 | −0.8 |
| Lamps, reflectors and electrical equipment | 26.1 | 25.3 | +0.8 |
| Identification of the vehicle | 3.1 | 2.6 | +0.5 |
| Tyres | 10.2 | 10.0 | +0.3 |
| Measure | Audi A4 | Mercedes-Benz C-Class |
|---|---|---|
| Repaired and passed the same day | 37.4% | 39.0% |
| Passed 1–10 days later | 58.9% | 57.5% |
| Median retest delay | 1.0 days | 1.0 days |
| Failures per 10,000 miles | 0.367 | 0.340 |
| Three-test clean streak | 33.4% | 38.4% |
| Same advisory repeated 3+ times | 31.9% | 27.0% |
Source: DVSA MOT bulk data · Window: 2019–2024 · n = 2,121,804 (tracked advisories) · Method: same vehicles followed to their next ordinary MOT; common publishable components only · Updated: 25 Sep 2026 · Release: dvsa-2024-v2 · CSV
Recalls, other countries and running costs, side by side
DVSA lists 36 recall campaigns matched to the Audi A4 and 158 to the Mercedes-Benz C-Class; more campaigns do not by themselves mean a less reliable car. Abroad, compare each model with that country's own average, because pass rates do not carry across rulebooks. Repair bills are catalogue estimates, not quotes.
| Measure | Audi A4 | Mercedes-Benz C-Class |
|---|---|---|
| DVSA recall campaigns listed | 36 | 158 |
| Finland Katsastus: fails, % (national average 26.3%) | 22.5 (30,550 inspections) | 35.3 (39,349 inspections) |
| Netherlands APK: fails, % (national average 50.8%) | 47.3 (41,406 inspections) | 48.1 (56,302 inspections) |
| Norway PKK: fails, % (national average 33.7%) | 37.4 (21,519 inspections) | 36.5 (16,299 inspections) |
| Expected MOT repair bill, £ (estimate) | £76 | £74 |
| Repair bill range, £ (catalogue range, not a 95% interval) | £76–£145 | £74–£141 |
Source: DVSA vehicle recalls register (OGL v3.0); Statens vegvesen PKK (CC BY 4.0), Traficom Katsastus (CC BY 4.0), RDW APK (CC0), adapted; UK repair price catalogue · Window: register as published; inspections 2024 · n = 205,425 (inspections abroad) · Method: recall campaigns matched by make and model, licensed-fleet denominator where available; abroad, samples below 500 suppressed and each model set against that country's own average, with no difference taken across countries; repair bill = chance of failing each item × its most common UK repair price, a catalogue estimate · Updated: 25 Sep 2026 · Release: dvsa-2024-v2 · CSV · licences and full notice
How to cite this comparison
MOT Risk Index (2026). Audi A4 vs Mercedes-Benz C-Class: MOT statistics 2024 (data release dvsa-2024-v2; full dataset motriskindex-families-2024-v5, DOI 10.5281/zenodo.22975051), updated 25 September 2026. motriskindex.co.uk/compare/audi-a4-vs-mercedes-c-class/
How the MOT Risk Index and every figure on this page are calculated: methodology.
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Audi A4 vs Mercedes-Benz C-Class: quick answers
Is the Audi A4 or the Mercedes-Benz C-Class more reliable?
Allowing for age, there is no practical difference (under 5 points apart): MOT Risk Index 87.4 for the Audi A4, 87.4 for the Mercedes-Benz C-Class (100 = normal for its age).
Does the Audi A4 or the Mercedes-Benz C-Class fail more MOTs?
27.9% of Audi A4 first tests and 25.9% of Mercedes-Benz C-Class first tests failed in 2024. These raw rates do not allow for age; the MOT Risk Index does.
Which should I buy, the Audi A4 or the Mercedes-Benz C-Class?
On MOT reliability neither is a practical winner. Choose the individual car with the cleaner MOT history and fewer repeated advisories.