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, estimated running costs, typical issues, and overall reliability. Based on 1,267,727 MOT tests (DVSA MOT data for tests in 2024, retests included).
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Quick Verdict
The Mercedes-Benz C-Class comes out slightly ahead with an 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 All-Model Avg | +1 pts | +2 ptsWinner |
| Est. Fuel Cost (petrol, 8,000 mi/yr) | £1,814 | £1,814 |
| Est. Insurance Group | 25-35 | 25-35 |
| Est. Depreciation/yr | £2,000-£3,500 | £2,000-£3,500 |
| Engine Size | 2.1L | 2.2L |
| Fuel Type(s) | Diesel, Petrol | Petrol, Hybrid |
| Segment | Premium | Premium |
| 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 |
Pass rates are the share of MOT tests that ended in a pass (DVSA MOT data for tests in 2024, retests included), across all years of each model. Best and worst years need at least 100 tests. Fuel cost, insurance group and depreciation are our rough estimates from engine size and make, not official figures.
Common Problems Comparison
Typical issues to check on cars of this type and age, not faults measured for these models.
Audi A4: Typical Issues to Check
- •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: Typical Issues to Check
- •Higher tyre and brake wear (larger engine)
- •Suspension wear on older models
- •Lighting defects (common on all cars)
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Audi A4 vs Mercedes-Benz C-Class FAQ
Can I compare an Audi A4 and Mercedes-Benz C-Class by registration plate?
Yes. Enter each car's UK registration plate on this page or use our free compare tool at carcostcheck.co.uk/compare to see MOT history, mileage, health scores and running costs for the exact vehicles you are considering, not just model averages.
Which is more reliable, the Audi A4 or Mercedes-Benz C-Class?
The Mercedes-Benz C-Class has the higher MOT pass rate, 84% compared to 83% for the Audi A4 (DVSA MOT data for tests in 2024, retests included).
Which is cheaper to run, the Audi A4 or Mercedes-Benz C-Class?
At 8,000 miles per year, the Audi A4 costs around £1,814 in fuel, while the Mercedes-Benz C-Class costs around £1,814 (our estimates for petrol versions from average engine size, with fuel at GOV.UK average pump prices for the week of 19 October 2026). On these estimates they cost the same in 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 an 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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