The short answer
Based on available data, the Audi S6 comes out ahead of the Audi S7 on fuel economy. Check the specs table and owner sentiment below for the full comparison before deciding between the two. Both are covered by real owner reports on CarWizz.
Overall
Sentiment is mixed and heavily dependent on the specific generation and powertrain. For the C7 generation (approximately 2013-2018) with the twin-turbo 4.0L V8 (4.0T), the vehicle is widely praised for its potent performance, refined luxury, and high-speed cruising capability, described as stable and quiet even at high speeds (e.g., 155 mph / 250 km/h). However, this generation is overshadowed by a very frequent and severe concern regarding catastrophic turbocharger failure, linked to oil screen design flaws, which can lead to engine destruction and extremely high repair costs.
Best version to buy
Insufficient owner data available to declare a consensus "best" version. For the C7 generation (4.0T), there is a strong emphasis on purchasing a vehicle with a comprehensive extended warranty that explicitly covers the turbochargers.
Known issues
Overall
Sentiment is divided and heavily dependent on the specific generation and powertrain. The vehicle is universally praised for its styling, which is noted to age exceptionally well, its potent performance, and its refined, high-quality interior. However, significant concerns center on reliability and maintenance costs, with a stark generational divide.
Best version to buy
Insufficient owner data available to declare a consensus "best" version. Data suggests a strong preference for the supercharged 3.0L V6 in the A7 over the turbocharged V8 in the S7 for its perceived reliability and lack of lag, though this is not a direct S7 comparison.
Known issues
The verdict
The Audi S6 is the better choice for most buyers.
It has better fuel economy on its best-equipped version than the Audi S7, based on the data above. If power matters more to you than running costs, the Audi S7 is worth a closer look instead.
Other comparisons
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Which is more reliable, the Audi S6 or the Audi S7?
Owner reports show similar reliability sentiment for the Audi S6 and the Audi S7. Check the known issues listed above for specific differences between the two.
Which is better for families, the Audi S6 or the Audi S7?
The Audi S6 seats more passengers than the Audi S7 on its catalogued best-equipped version. Body type also differs: the Audi S6 is classed as a Sedan, the Audi S7 as a Liftback.
Which has better fuel economy, the Audi S6 or the Audi S7?
The Audi S6 is more fuel-efficient on paper: 9.2-9.4 L/100km combined versus 9.3-9.5 L/100km for the Audi S7, based on the best-equipped catalogued version of each.
Which is cheaper to maintain, the Audi S6 or the Audi S7?
Exact maintenance costs aren't in our data, but reliability signals above are the closest proxy: fewer reported issues generally means lower repair costs over time.