Audi A3 vs Mercedes-Benz A-Class: which fails its MOT less?
Allowing for age, the Audi A3 fails its MOT less often than the Mercedes-Benz A-Class.
- less often than the Mercedes-Benz A-Class, at the same age
- 10.0%less often than the Mercedes-Benz A-Class, at the same age
MOTs passed in 2024: Audi A3 78.6%, Mercedes-Benz A-Class 82.1%
These pass rates point the other way because the two fleets differ in age.
Data: DVSA MOT results · 2024 · 721,191 tests
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Which fails less for its age?
Allowing for age, the Audi A3 fails less often: MOT Risk Index 84.8 against 94.2 (100 = normal for its age; difference 9.4, 95% CI 8.7–10.2).
Both fail less often than normal for their age.
| Measure | Audi A3 | Mercedes-Benz A-Class | Years |
|---|---|---|---|
| Passed at the first attempt, % | 74.0 | 78.2 | 2024 |
| MOT Risk Index (100 = normal) | 84.8 | 94.2 | 2024 |
| 95% interval of the index | 84.3–85.2 | 93.6–94.8 | 2024 |
| Rank among 761 models (1 = fails least for its age) | 304 | 391 | 2024 |
| First tests | 389,739 | 331,452 | 2024 |
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After defects were fixed at the test centre
78.6% of Audi A3 tests and 82.1% of Mercedes-Benz A-Class tests passed, including defects fixed during the test. This is a different outcome from passing at the first attempt.
Raw pass rates point the other way because the fleets differ in age.
What explains the difference?
The clearest difference is suspension: against its own class and age, the Audi A3 runs +0.4 items per 100 tests and the Mercedes-Benz A-Class −2.8, so the Mercedes-Benz A-Class has 3.3 fewer per 100 tests (95% interval 3.2 to 3.3).
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 A3 | Mercedes-Benz A-Class |
|---|---|---|
| Dangerous defects per 100 tests | 11.4 | 9.0 |
| Advisory items per 100 tests | 116.3 | 91.0 |
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 11: the difference is clear at 14 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 9.8 extra failed tests per 100 for the Mercedes-Benz A-Class (a sum of yearly rates, not the chance of one car failing).
| Age | Difference, pp | 95% interval | Reading |
|---|---|---|---|
| 3 | −0.4 | −0.7 to −0.1 | Audi A3 fails less |
| 4 | −1.3 | −1.6 to −0.9 | Audi A3 fails less |
| 5 | −2.5 | −2.8 to −2.2 | Audi A3 fails less |
| 6 | −2.9 | −3.2 to −2.5 | Audi A3 fails less |
| 7 | −3.2 | −3.6 to −2.8 | Audi A3 fails less |
| 8 | −3.2 | −3.7 to −2.8 | Audi A3 fails less |
| 9 | −2.5 | −3.1 to −2.0 | Audi A3 fails less |
| 10 | −0.8 | −1.4 to −0.1 | Audi A3 fails less |
| 11 | +1.5 | +0.8 to +2.3 | Mercedes-Benz A-Class fails less |
| 12 | +1.8 | +1.0 to +2.6 | Mercedes-Benz A-Class fails less |
| 13 | +1.5 | +0.7 to +2.3 | Mercedes-Benz A-Class fails less |
| 14 | +1.7 | +0.9 to +2.5 | Mercedes-Benz A-Class fails less |
| 15 | +1.7 | +0.8 to +2.6 | Mercedes-Benz A-Class fails less |
| 16 | +1.2 | +0.2 to +2.2 | Mercedes-Benz A-Class fails less |
| 17 | +1.0 | −0.1 to +2.2 | not distinguishable |
| 18 | +0.5 | −0.9 to +1.9 | not distinguishable |
| 19 | −0.0 | −1.7 to +1.7 | not distinguishable |
| Age band | Ages included | Audi A3, % | Mercedes-Benz A-Class, % | Difference, pp | 95% interval | Reading |
|---|---|---|---|---|---|---|
| 3–5 | 3–5 | 12.0 | 13.3 | −1.2 | −1.4 to −1.1 | Audi A3 fails less |
| 6–10 | 6–10 | 20.7 | 22.1 | −1.4 | −1.5 to −1.2 | Audi A3 fails less |
| 11+ | 11–20+ | 39.4 | 39.0 | +0.4 | +0.2 to +0.6 | Mercedes-Benz A-Class fails less |
Source: DVSA MOT bulk data · Window: 2019–2024 · n = 3,954,074 (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 A3 runs +0.4 items per 100 tests and the Mercedes-Benz A-Class −2.8, so the Mercedes-Benz A-Class has 3.3 fewer per 100 tests (95% interval 3.2 to 3.3).
| Component group | Audi A3 vs its class | Mercedes-Benz A-Class vs its class | Gap, Audi A3 minus Mercedes-Benz A-Class | 95% interval | Reading |
|---|---|---|---|---|---|
| Suspension | +0.4 | −2.8 | +3.3 | +3.2 to +3.3 | Mercedes-Benz A-Class fails less |
| Body, chassis, structure | +1.7 | −0.6 | +2.2 | +2.2 to +2.3 | Mercedes-Benz A-Class fails less |
| Brakes | −2.3 | −0.9 | −1.4 | −1.4 to −1.3 | Audi A3 fails less |
| Seat belts and supplementary restraint systems | −0.0 | +0.8 | −0.8 | −0.8 to −0.8 | Audi A3 fails less |
| Tyres | +1.5 | +0.8 | +0.8 | +0.7 to +0.8 | Mercedes-Benz A-Class fails less |
| Visibility | −0.6 | +0.1 | −0.7 | −0.8 to −0.7 | Audi A3 fails less |
Source: DVSA MOT bulk data · Window: 2019–2024 · n = 4,012,103 (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 on the Audi A3 carries 1.6 percentage points more extra risk of failing again than on the Mercedes-Benz A-Class.
| Measure | Audi A3 | Mercedes-Benz A-Class |
|---|---|---|
| After a failed test, % | 33.7 | 29.6 |
| After a passed test, % | 21.7 | 19.1 |
| Extra risk carried by a failure, pp | 12.0 | 10.4 |
Source: DVSA MOT bulk data · Window: 2019–2024 · n = 183,424 (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 steering: 11.0% on the Audi A3 against 2.9% on the Mercedes-Benz A-Class failed on the same item at the next MOT.
| Component | Audi A3 | Mercedes-Benz A-Class | Difference, pp |
|---|---|---|---|
| Steering | 11.0 | 2.9 | +8.1 |
| Suspension | 22.4 | 18.5 | +3.9 |
| Body, chassis, structure | 19.2 | 15.6 | +3.6 |
| Noise, emissions and leaks | 7.7 | 5.7 | +2.1 |
| Visibility | 11.5 | 9.5 | +2.0 |
| Lamps, reflectors and electrical equipment | 24.6 | 26.1 | −1.5 |
| Tyres | 10.2 | 8.8 | +1.4 |
| Road wheels | 0.9 | 1.5 | −0.5 |
| Brakes | 10.0 | 9.8 | +0.3 |
| Seat belts and supplementary restraint systems | 4.0 | 4.3 | −0.2 |
| Measure | Audi A3 | Mercedes-Benz A-Class |
|---|---|---|
| Repaired and passed the same day | 45.6% | 48.3% |
| Passed 1–10 days later | 51.8% | 49.3% |
| Median retest delay | 1.0 days | 1.0 days |
| Failures per 10,000 miles | 0.363 | 0.313 |
| Three-test clean streak | 38.1% | 42.3% |
| Same advisory repeated 3+ times | 29.8% | 20.0% |
Source: DVSA MOT bulk data · Window: 2019–2024 · n = 2,042,718 (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 26 recall campaigns matched to the Audi A3 and 100 to the Mercedes-Benz A-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 A3 | Mercedes-Benz A-Class |
|---|---|---|
| DVSA recall campaigns listed | 26 | 100 |
| Finland Katsastus: fails, % (national average 26.3%) | 21.3 (17,390 inspections) | 17.3 (11,240 inspections) |
| Netherlands APK: fails, % (national average 50.8%) | 44.4 (63,554 inspections) | 43.4 (49,192 inspections) |
| Norway PKK: fails, % (national average 33.7%) | 34.4 (19,635 inspections) | 29.1 (6,875 inspections) |
| Expected MOT repair bill, £ (estimate) | £69 | £40 |
| Repair bill range, £ (catalogue range, not a 95% interval) | £69–£131 | £40–£77 |
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 = 167,886 (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 A3 vs Mercedes-Benz A-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-a3-vs-mercedes-a-class/
How the MOT Risk Index and every figure on this page are calculated: methodology.
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Audi A3 vs Mercedes-Benz A-Class: quick answers
Is the Audi A3 or the Mercedes-Benz A-Class more reliable?
Allowing for age, the Audi A3 fails less often: MOT Risk Index 84.8 against 94.2 (100 = normal for its age; difference 9.4, 95% CI 8.7–10.2).
Does the Audi A3 or the Mercedes-Benz A-Class fail more MOTs?
26.0% of Audi A3 first tests and 21.8% of Mercedes-Benz A-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 A3 or the Mercedes-Benz A-Class?
If MOT reliability decides it, the evidence favours the Audi A3. Still check the individual car's MOT history: these figures describe whole model populations.