Audi A4 vs BMW 3 Series
Take the BMW 3 Series for lower age-adjusted MOT risk: its index is 75.6 versus 84.6 for the Audi A4, and the 95% confidence intervals do not overlap.
Lower is better. The index adjusts for each fleet's exact age profile; the raw failure rate below does not. The index gap is 9.0 points. Data release dvsa-2024-v1.
Side-by-side evidence
| Measure | Audi A4 | BMW 3 Series |
|---|---|---|
| Age-adjusted MOT Risk Index | 84.6 (84.1–85.0) | 75.6 (75.3–75.9) |
| Raw initial failure rate | 25.09% | 24.75% |
| Dangerous defects per 100 tests | 14.78 | 15.66 |
| Initial tests | 406,182 | 675,043 |
Where their MOT failures diverge
These are component groups present in both models' published top-six failure lists, sorted by the absolute gap. A positive difference means the Audi A4 records more failure items; a negative one means the BMW 3 Series does.
| Component group | Audi A4 | BMW 3 Series | Difference | Lower rate |
|---|---|---|---|---|
| Brakes | 12.1 | 17.0 | -4.9 pp | Audi A4 |
| Suspension | 23.7 | 19.1 | +4.6 pp | BMW 3 Series |
| Visibility | 12.0 | 15.4 | -3.4 pp | Audi A4 |
| Lamps, reflectors and electrical equipment | 20.3 | 22.4 | -2.1 pp | Audi A4 |
| Tyres | 13.3 | 13.0 | +0.3 pp | BMW 3 Series |
Counts are defect items, not the share of cars: one failed test can contain several items. A group absent from a model's top six is not treated as zero.
What the six-year test history says
The longitudinal layer follows the same vehicles between MOTs from 2019 to 2024. It separates a one-day retest from the harder question of what returns next year, and puts failures against miles actually driven.
| Component | Audi A4 | BMW 3 Series | Difference | Tracked advisories |
|---|---|---|---|---|
| Steering | 13.9% | 5.1% | +8.8 pp | 10,978 / 20,815 |
| Body, chassis, structure | 15.1% | 6.7% | +8.4 pp | 25,183 / 47,065 |
| Brakes | 10.8% | 13.6% | -2.8 pp | 241,893 / 474,044 |
| Lamps, reflectors and electrical equipment | 26.1% | 23.4% | +2.7 pp | 16,557 / 19,761 |
| Visibility | 11.4% | 13.1% | -1.7 pp | 1,003 / 1,917 |
| Seat belts and supplementary restraint systems | 3.9% | 5.3% | -1.3 pp | 4,549 / 7,381 |
| Road wheels | 1.3% | 2.5% | -1.3 pp | 4,071 / 14,944 |
| Tyres | 10.2% | 10.7% | -0.5 pp | 315,154 / 492,067 |
| Noise, emissions and leaks | 7.8% | 7.4% | +0.4 pp | 52,511 / 138,324 |
| Identification of the vehicle | 3.1% | 2.8% | +0.3 pp | 30,822 / 52,550 |
| Measure | Audi A4 | BMW 3 Series |
|---|---|---|
| Repaired and passed the same day | 37.4% | 35.6% |
| Passed 1–10 days later | 58.9% | 60.3% |
| Median retest delay | 1.0 days | 1.0 days |
| Failures per 10,000 miles | 0.367 | 0.397 |
| Three-test clean streak | 33.4% | 34.5% |
| Same advisory repeated 3+ times | 31.9% | 34.4% |
Care proxy is descriptive, not a claim about an owner's character: a clean streak means three or more consecutive tests with nothing recorded; the repeat measure means the same advisory appeared at least three times.
Safety recalls
| Model | Campaigns listed | Per 10,000 licensed |
|---|---|---|
| Audi A4 | 36 | 1.63 |
| BMW 3 Series | 114 | 2.54 |
More campaigns do not by themselves mean a less reliable car: recalls are manufacturer remedies, and the licensed-fleet denominator is unavailable for some families. Check a registration for outstanding work before buying.
Do other countries see the same thing?
Both models appear in the same independent national inspection datasets below. Compare each model with that country's own average; absolute pass rates are not portable between rulebooks.
| Country / test | Model | Model fails | National average | Position | Inspections |
|---|---|---|---|---|---|
| Finland · Katsastus | Audi A4 | 22.5% | 26.3% | -3.8 pp | 30,550 |
| Finland · Katsastus | BMW 3 Series | 32.1% | 26.3% | +5.8 pp | 30,097 |
| Netherlands · APK | Audi A4 | 36.5% | 50.9% | -14.4 pp | 17,613 |
| Netherlands · APK | BMW 3 Series | 49.3% | 50.9% | -1.6 pp | 75,436 |
Sources are the national PKK, Katsastus and APK datasets recorded in each family artifact. Position is model failure rate minus that country's national rate.
Quick answers
- Is the Audi A4 or the BMW 3 Series more reliable?
- The BMW 3 Series has the stronger age-adjusted MOT result: index 75.6 against 84.6 for the Audi A4, with non-overlapping 95% confidence intervals.
- Does the Audi A4 or the BMW 3 Series fail more MOTs?
- 25.09% of Audi A4 initial tests and 24.75% of BMW 3 Series initial tests found a failing defect in 2024. The lower raw rate belongs to the BMW 3 Series, but the age-adjusted index is the fairer model comparison because the fleets can be different ages.
- What are the main MOT problem areas on the Audi A4 and BMW 3 Series?
- The leading published failure group for the Audi A4 is suspension at 23.7 items per 100 tests; for the BMW 3 Series it is lamps, reflectors and electrical equipment at 22.4 per 100.
- Should I buy a Audi A4 or a BMW 3 Series?
- If MOT reliability is the deciding factor, the BMW 3 Series is the evidence-led choice. Still check the individual car's MOT history and condition: these figures describe whole model populations, not a particular vehicle.
Model pages and nearby comparisons
See the Audi A3 and Volkswagen Golf comparisonSee the Audi A4 and Mercedes C Class comparisonSee the Audi A3 and Vauxhall Astra comparison
Browse all car reliability comparisons.
How to read and cite this comparison
Scope: class-4 vehicles, initial tests only, Great Britain 2024. PRS fixed-on-the-spot results count as failures because a defect was present on arrival. Index = observed initial failures ÷ age-profile-expected failures × 100; intervals are 95% confidence intervals. Every model family combines all generations and engines. Full method: methodology.
Cite: MOT Risk Index (2026). Audi A4 vs BMW 3 Series: MOT reliability comparison, 2024 (dvsa-2024-v1). https://motriskindex.co.uk/compare/audi-a4-vs-bmw-3-series/