The Audi A4 is a mid-size car (D segment), while the Audi A6 is a larger executive saloon (E segment) – it is about 20 cm longer, more spacious and has a more powerful engine range. The A4 competes with the BMW 3 Series and Mercedes C-Class, while the A6 competes with the BMW 5 Series and Mercedes E-Class. So, choosing between the Audi A4 and A6 comes down to how much space and comfort you need and how much you're willing to spend on maintenance.
To sum it up
- A4 – segment D, A6 – segment E (upper class).
- The Audi A6 C8 is around 21 cm longer than the Audi A4 B9 and has a wheelbase that is around 10 cm longer – this means more space in the rear and trunk.
- The Audi A6 offers more powerful engines (including a V6 and, in the RS6, a V8) and better sound insulation, while the Audi A4 is lighter and cheaper to run.
- From 2024, the successor to the Audi A4 with an internal combustion engine will be Audi A5 (B10) , and the A6 will retain its name.
Audi A4 and A6 – two segments, two classes.
Audi A4 — is a mid-range model. In its latest generation, the B9 (2015–2024), it was offered as a sedan, Avant wagon, and allroad. It's a car for families or those who drive a lot but don't need a sedan.
Audi A6 — is a luxury car, often chosen for corporate fleets and long-distance travel. The C8 generation (since 2018) is available in sedan, wagon, and allroad body styles, as well as sportier versions, including the S6 and RS6 Avant.
Dimensions and capacity – A4 B9 vs. A6 C8
The A4 B9 sedan is approximately 4.73–4.76 m long, with a wheelbase of 2.82 m. The A6 C8 sedan is approximately 4.94 m long, with a wheelbase of approximately 2.92 m. This extra 10 cm between the axles is particularly noticeable in the rear seats: tall passengers in the A6 have significantly more legroom.
The trunk capacity of the A4 B9 sedan is approximately 460 liters, while the A6 C8 sedan is approximately 530 liters (this figure is for versions without the hybrid drive, which reduces capacity). In the wagon versions, the difference is smaller, but still in favor of the A6.
Engines, performance and comfort
The A4 B9 lineup featured engines ranging from 1.4 to 3.0 liters—TFSI gasoline and TDI diesel—with outputs starting from 122 hp in the base models. The most powerful models were the S4 and RS4 Avant.
The Audi A6 C8 is offered in a higher price segment, with 2.0- and 3.0-liter V6 engines (petrol, diesel, and plug-in hybrid) producing 163 hp and higher, while the RS6 Avant is equipped with a 4.0-liter V8. The A6 also comes standard with improved cabin soundproofing and more advanced features, while air suspension and rear-axle steering are available as options. However, the A6 is heavier, so with the same engine, it will generally consume slightly more fuel than the A4.
Comparison Chart: Audi A4 and A6
| Characteristic | Audi A4 (B9) | Audi A6 (C8) |
|---|---|---|
| Segment | D – middle class | E – highest class |
| Years of production | 2015–2024 | since 2018 |
| Length (sedan) | approximately 4.73–4.76 m | approximately 4.94 m |
| Wheelbase | approximately 2.82 m | approximately 2.92 m |
| Trunk (sedan) | approximately 460 l | approximately 530 l |
| Engines | 1.4–3.0, from 122 hp. | 2.0–4.0, from 163 hp. |
| Rivals | BMW 3 Series, Mercedes C-Class | BMW 5 Series, Mercedes E-Class |
| Operating costs | Below | Taller (bigger wheels, brakes, heavier vehicle) |
The dimensions and volumes indicated are approximate – the exact values depend on the body style, engine and year of manufacture.
Audi A4 B8 vs. Audi A6 C6 – Aftermarket Comparison
Among used cars Audi A4 B8 (2007–2015) is often compared to Audi A6 C6 (2004–2011), as both models currently cost roughly the same. The proportions are similar: the A6 C6 sedan is approximately 4.92 m long and has a trunk capacity of approximately 546 liters, while the A4 B8 sedan is approximately 4.70 m long and 480 liters. The wheelbases are 2.84 m and 2.81 m, respectively, so the difference in rear passenger space is smaller than in newer generations.
It's worth remembering that the A6 C6 is a model released several years ago. The C6 lineup featured engines ranging from 2.0 TDI to V6 and 4.2 V8, while the A4 B8 offered engines from 1.8 TFSI to 3.2 FSI. However, the deciding factor when purchasing a car is its condition and documented service history, not the model itself.
Audi A4 or A6 – which one to choose?
- Choose Audi A4, If you mostly drive in the city, park in tight garages, only carry children in the back seat, and want to reduce your fuel, tire, and maintenance costs.
- Choose Audi A6, If you drive a lot on the road, often carry adults in the back seat, need a larger trunk, or value silence and prestige.
- Buying a new car? The new Audi A4 will no longer be available in showrooms – it was replaced in 2024 by the Audi A5 (B10 generation), available in liftback and wagon body styles. The new Audi A6 (C9) debuted in 2025 and – following Audi's naming decision – retained its current name. The electric version is called the A6 e-tron.
- Buying a used car? Compare specific models: A newer Audi A4 may be a better choice than an older A6 at a similar price, as higher-end cars cost more to repair.
Frequently Asked Questions (FAQ)
What is the difference between the Audi A4 and A6?
The Audi A4 is a midsize car (D segment), while the Audi A6 is an executive car (E segment). The Audi A6 is approximately 20 cm longer, has a larger wheelbase and trunk, more powerful engines, and better sound insulation, but is more expensive to purchase and maintain.
Audi A4 or A6 – which one is cheaper to maintain?
The Audi A4 is typically chosen. It's lighter, has smaller wheels and brakes, and a less powerful engine, resulting in lower fuel consumption and cheaper parts. However, the final price depends on the specific engine version and the car's condition.
Is the Audi A6 significantly larger than the A4?
In the B9 and C8 generations, the A6 sedan is approximately 21 cm longer, and its wheelbase is approximately 10 cm longer. This is most noticeable in the rear seats and trunk.
Audi A4 B8 or A6 C6 – which is better?
The Audi A6 C6 offers more space and a larger trunk (approximately 546 liters in the sedan compared to approximately 480 liters in the A4 B8), but it is an older model. The A4 B8 is generally younger and less expensive to repair. It's worth basing your choice on the car's technical condition and service history.
Does Audi still produce the A4?
The B9-generation Audi A4 with combustion engines replaced the Audi A5 (B10) in 2024. In fact, it is the successor to the A4 in the same class, competing with the BMW 3 Series and Mercedes-Benz C-Class.
See also
- What is the difference between gasoline and diesel fuel?
- What is the difference between 5W30 and 5W40 oils?
- What is the difference between twin turbo and biturbo?
- What is the difference between E5 and E10 gasoline?