The 2015 Audi S6 with its charismatic 4.0-liter V8 gets 20 MPG combined. This isn’t a hybrid posing as a performance car, it’s a genuine Autobahn stormer in understated luxury, and the fuel economy reflects that. The S6 buyer likely isn’t cross-shopping with a Prius, they’re seeking a refined, rapid sedan and are willing to pay the price at the pump for the driving experience. They accept the compromise because of the instantaneous thrust, a complex all-wheel-drive system, and a cabin that whispers luxury even at triple-digit speeds.

City and highway performance

The EPA estimates break down that 20 MPG. The city MPG rating is a more sobering 17. Stop-and-go traffic will quickly drain the tank, particularly if you’re frequently tapping into the V8’s considerable power. On the open road, the S6 fares considerably better, achieving a respectable 27 MPG highway. This reflects the engine’s ability to cruise effortlessly at higher speeds, using the seven-speed automatic transmission to keep the engine in its sweet spot. Remember that these figures are achieved under controlled conditions. Aggressive driving, a heavy foot, or even strong headwinds can easily reduce these numbers.

Annual fuel cost

The EPA estimates that the annual fuel cost for the 2015 Audi S6 is $2,900. This calculation is based on driving 15,000 miles per year, with a specific percentage of those miles driven in the city versus on the highway, using the national average fuel price at the time of calculation. This figure is a useful benchmark for comparing fuel costs across different vehicles, but individual expenses can vary significantly based on driving habits and local fuel prices.

If your daily commute is primarily stop-and-go, or if premium fuel prices are particularly high in your area, expect to exceed this estimate.

Real-world expectations

While the EPA provides a standardized test, real-world fuel economy can vary a lot. Expect to see numbers fluctuate based on driving style, traffic conditions, and even tire pressure. Some owners report achieving closer to the EPA highway figure on long road trips, while others struggle to break 15 MPG in the city with enthusiastic driving.

The key takeaway is to manage expectations. The S6 rewards a measured approach, but its performance tempts drivers to exploit its capabilities. Factor in around $250 per month for fuel, depending on mileage and driving style. For all Audi fuel economy data, check out our brand page.

How it compares

Compared to its competitors, the 2015 Audi S6’s fuel economy lands in a predictable range. The BMW 550i xDrive, with its similar V8 engine, delivers comparable numbers, often hovering around 16 city/25 highway. The Mercedes-Benz E550 from that year is in the same ballpark, further solidifying the understanding that big power equals a compromise in efficiency. A more modern comparison could be made to the 2024 BMW M550i xDrive, which also achieves around 20 mpg combined.

Buyers considering the S6 prioritize performance and luxury over outright fuel efficiency; if fuel economy is a primary concern, they might be better served by a smaller-engined model or considering hybrid alternatives. To see S6 MPG across all years, check out the S6 MPG across all years page.

Tips to maximize efficiency

One often overlooked aspect of fuel efficiency is tire pressure. Ensure your tires are inflated to the recommended pressure listed on the driver’s side doorjamb. Underinflated tires increase rolling resistance, which forces the engine to work harder and consume more fuel. A simple tire pressure check can noticeably improve your MPG, especially on long journeys.

Anticipate traffic flow and practice smooth acceleration and braking. The S6’s powerful engine responds well to gentle inputs. Avoid aggressive starts and hard braking, as these actions waste fuel. Maintaining a steady speed and anticipating traffic lights will help you maximize fuel economy, even in city driving.

Use the Audi Drive Select system to your advantage. Select the “Efficiency” mode when possible, which optimizes various vehicle settings for fuel conservation. This mode can adjust throttle response, transmission shift points, and even climate control settings to minimize energy consumption. While it might slightly reduce performance, it can make a noticeable difference on long commutes.

Regular maintenance is critical for optimal fuel economy. Ensure your engine is properly tuned, and that air filters are clean. A well-maintained engine operates more efficiently, resulting in better MPG. Schedule regular service appointments to keep your S6 running at its peak performance.