Audi A4 vs Audi A6
Figures updated
The Audi A4 and Audi A6 are two of the UK's most popular executive cars. We compare the B9 (2015–2024) A4 and the C9 (2025–) A6 on price, size, boot space, performance, safety and running costs, plus how reliable each has been across 367,538 real MOT tests.
The short answer
The Audi A6 comes out ahead, with the bigger boot and the better MOT record; the Audi A4 is close on everything else.
- The Audi A6 has the biggest boot: 492 litres, 32 more than the Audi A4.
- The Audi A6 has the better MOT record. Like for like on age and mileage, the Audi A4 fails its MOT about 24% more often.
| Figure | Audi A4B9 (2015–2024), 4-door saloon | Audi A6C9 (2025–), 4-door saloon |
|---|---|---|
| Price and practicality | ||
| Price newUK list prices, across the range | – | from £54,060October 2026 price list |
| Body | 4-door saloon | 4-door saloon |
| Seats | 5 | 5 |
| BootSeats up / folded | 460 litres | 492 litres (best) |
| Length | 4,762mm | 4,999mm |
| WidthWithout mirrors | 1,847mm | 1,875mm |
| Height | 1,387mm | 1,452mm |
| Performance | ||
| Power | 136–265 PS | 204–299 PS (best) |
| 0–62mph | 5.5–9.5 sec (best) | 6.0–8.2 sec |
| Safety | ||
| Euro NCAP ratingTests get tougher each year | ★★★★★ (2015) | ★★★★★ (2024) |
| Economy and emissions | ||
| Fuel types | Diesel | Electric, Hybrid, Petrol, Plug-in hybrid |
| Official economyVersions of this generation | 54.3–74.3 mpg | 36.2–55.4 mpg |
| CO2 | 99–137 g/km | 32–178 g/km |
| Electric range | – | 329–462 miles |
| Running costs at 7,500 miles a year | ||
| Petrol or hybrid171.8p a litre, today's UK average | – | £1,450 (40.4 mpg) |
| Diesel198.4p a litre | £1,030 (65.7 mpg) | – |
| Electric, charged at home26.3p per kWh standard tariff | – | £548 (4 mi/kWh) |
| Cheapest version to fuelWhichever fuel costs least | £1,030 (diesel) | £548 (electric) |
| Car tax, registered 2001 to 2017Taxed on CO2; newer cars pay a flat £200 | £20 to £790 | £20 to £790 |
| Reliability from real MOT tests | ||
| Reliability score | 125Well above average | 155Well above average (best) |
| Failed MOT first time (ages 3–20) | 27.1% | 20.9% (best) |
| Failed at 3 years old | 11.8% | 9.5% (best) |
| Failed at 5 years old | 14.5% | 11.2% (best) |
| Failed at 10 years old | 26.3% | 20.5% (best) |
| Most common MOT fault | Coil spring (3.6% of tests) | Tread depth (2.9% of tests) |
| Fails more than average on | Nothing stands out | Nothing stands out |
| MOT tests analysed | 244,913 | 122,625 |
| About the cars | ||
| Type | Executive car | Executive car |
| Owners' average miles a year | 9,900 | 11,000 |
| On sale | 2015–2024 | 2025 on |
Green marks the better figure where the difference is more than 3%. Reliability figures cover every version of each model tested in the year. Running costs use the typical official economy of recent versions (WLTP where available); real-world economy is usually a little worse for every car.
More comparisons
Frequently asked questions
›Is the Audi A4 or the Audi A6 more reliable?
The Audi A6. Like for like on age and mileage, the Audi A4 fails its MOT about 24% more often (reliability scores 155 and 125, where 100 is average). 20.9% of Audi A6s and 27.1% of Audi A4s failed first time in 2024.
›Which is bigger, the Audi A4 or the Audi A6?
The Audi A6 is 237mm longer (4,999mm against 4,762mm). The Audi A6 has the bigger boot: 492 litres against 460.
›Which is safer, the Audi A4 or the Audi A6?
Euro NCAP gave the Audi A4 5 stars (2015) and the Audi A6 5 stars (2024). Euro NCAP makes its tests tougher every few years, so ratings from different years aren't directly comparable.
›Should I buy the Audi A4 or the Audi A6?
The Audi A6 comes out ahead, with the bigger boot and the better MOT record; the Audi A4 is close on everything else. The comparison above sets out price, space, performance, safety, running costs and reliability side by side.
Sources: manufacturers' UK specifications and price lists and Euro NCAP (listed on each model's page); DVSA anonymised MOT tests 2024 (Open Government Licence v3.0); Vehicle Certification Agency car fuel data, © Crown copyright, VCA cannot accept liability for its accuracy; fuel prices from the GOV.UK Fuel Finder scheme. Photos from Wikimedia Commons, credited under each picture.