Audi A4 vs Mercedes-Benz C-Class: Compare by Reg (2026)
Side-by-side comparison of the Audi A4 and Mercedes-Benz C-Class, covering MOT pass rates, running costs, common faults, and overall reliability. Based on 1,267,727 real MOT tests.
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Quick Verdict
The Mercedes-Benz C-Class comes out slightly ahead with a 84% MOT pass rate versus 83% for the Audi A4. Both cars are competitive in this segment, but the Mercedes-Benz C-Class has a small edge on reliability. Consider test driving both before making your decision.
Audi A4
83%
MOT pass rate
491,535 tests
Mercedes-Benz C-Class
84%
MOT pass rate
776,192 tests
More reliableFull Comparison: Audi A4 vs Mercedes-Benz C-Class
| Category | Audi A4 | Mercedes-Benz C-Class |
|---|---|---|
| MOT Pass Rate | 83% | 84%Winner |
| MOT Fail Rate | 17% | 16%Winner |
| vs National Avg | +1 pts | +2 ptsWinner |
| Est. Fuel Cost (8,000 mi/yr) | £1,434 | £1,115Winner |
| Insurance Group | 25-35 | 15-25 |
| Est. Depreciation/yr | £2,000-£3,500 | £1,500-£3,000 |
| Engine Size | 2.1L | 2.2L |
| Fuel Type(s) | Petrol, Diesel | Hybrid, Petrol, Diesel |
| Segment | Premium | Family car |
| Avg Mileage | 120,108 mi | 97,926 miWinner |
| MOT Tests Analysed | 491,535 | 776,192 |
| Model Years | 27 years | 32 years |
| Best Year | 2021 (96%)Winner | 2020 (92%) |
| Worst Year | 1995 (61%) | 2004 (72%)Winner |
| Reliability Trend | Improving | Improving |
Common Problems Comparison
Audi A4 Known Issues
- •DPF and emissions issues (diesel models)
- •Higher tyre and brake wear (larger engine)
- •Suspension wear on older models
- •Lighting defects (common on all cars)
Mercedes-Benz C-Class Known Issues
- •DPF and emissions issues (diesel models)
- •Higher tyre and brake wear (larger engine)
- •Suspension wear on older models
- •Lighting defects (common on all cars)
Check a Specific Audi A4
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Audi A4 vs Mercedes-Benz C-Class FAQ
Which is more reliable, the Audi A4 or Mercedes-Benz C-Class?
Based on MOT data, the Mercedes-Benz C-Class is more reliable with a 84% pass rate, compared to 83% for the Audi A4.
Which is cheaper to run?
At 8,000 miles per year, the Audi A4 costs around £1,434 in fuel, while the Mercedes-Benz C-Class costs around £1,115. The Mercedes-Benz C-Class is cheaper on fuel. Insurance, depreciation, and repair costs also factor into total running costs.
Should I buy a Audi A4 or Mercedes-Benz C-Class?
The Mercedes-Benz C-Class comes out slightly ahead with a 84% MOT pass rate versus 83% for the Audi A4. Both cars are competitive in this segment, but the Mercedes-Benz C-Class has a small edge on reliability. Consider test driving both before making your decision.
Audi A4 Running Costs
Full breakdown of annual costs, reliability, and MOT data
Mercedes-Benz C-Class Running Costs
Full breakdown of annual costs, reliability, and MOT data
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