22 MPG combined. Let’s be honest: nobody buys a 2015 Audi A8 with the 4.0L V8 expecting Prius-like efficiency. This car is about effortless power, executive-class comfort, and understated confidence. The fact that it manages to achieve a combined figure in the low twenties is almost a secondary consideration, but a welcome one nonetheless, especially when driving across state lines.

City and highway performance

The A8’s official EPA ratings reveal the divided nature of this flagship sedan. In the city, the 4.0L V8 and its automatic transmission are expected to return 18 MPG. Stop-and-go traffic and frequent red lights will quickly reduce that number. The engine’s considerable displacement always requires a certain amount of fuel. But on the open road, the A8 transforms. The highway MPG figure of 30 demonstrates the engine’s ability to cruise efficiently, aided by careful gearing and cylinder deactivation technology that allows the engine to run on fewer cylinders when full power isn’t needed. This difference between city and highway figures shows the A8’s ability to adapt to different driving environments.

Annual fuel cost

The EPA estimates that the annual fuel cost for the 2015 Audi A8 4.0L V8 will be $2,650. This figure is based on driving 15,000 miles per year and using the national average fuel prices for premium gasoline at the time the rating was established. Keep in mind that this is simply an estimate, and your actual fuel costs will vary depending on your driving habits, local fuel prices, and the actual miles you drive each year. Drivers who primarily stick to city driving should realistically expect to spend considerably more, though those who spend more time on the highway may see slightly lower costs.

Real-world expectations

While EPA ratings provide a useful baseline, real-world fuel economy often differs. The A8’s fuel consumption is heavily influenced by driving style. A heavy foot will quickly erode the 22 MPG combined rating, while a more restrained approach can often match or even slightly exceed it, especially on long highway journeys. Regional variations in fuel formulations and ambient temperatures can impact observed fuel economy. Consider the EPA ratings as a guide, but don’t be surprised if your personal experience varies.

How it compares

The 2015 Audi A8 4.0L V8 sits in a competitive segment of large luxury sedans. The BMW 750i from the same year, also featuring a turbocharged V8, posts similar figures around 17 MPG city and 25 MPG highway. A Mercedes-Benz S550, with its own V8, comes in very close too. Meanwhile, the Porsche Panamera S with its twin-turbo V6 managed slightly better highway figures. The A8 buyer isn’t simply chasing the highest MPG figure; they prioritize a blend of performance, luxury, and brand cachet. The slight variations in fuel economy between these vehicles are often less important than other factors, such as interior appointments, technology features, and the driving experience.

Tips to maximize efficiency

Gentle acceleration is key. The A8’s powerful V8 responds eagerly to throttle inputs, but using that power comes at a cost. Smooth, gradual acceleration will minimize fuel consumption, especially in city driving.

Use cruise control on the highway. Maintaining a consistent speed not only improves fuel efficiency but also reduces driver fatigue on long trips, which the A8 is supremely capable of completing. Avoid frequent acceleration and braking to get the best mileage.

Keep tires properly inflated. Check your tire pressures regularly and ensure they are inflated to the recommended levels. Underinflated tires increase rolling resistance, which can significantly reduce fuel economy. This is a simple maintenance task that can have a noticeable impact.

Reduce unnecessary weight. Carrying excessive cargo in the trunk or cabin adds weight to the vehicle, forcing the engine to work harder and consume more fuel. Remove any items that aren’t essential, particularly for city driving.

Following these simple tips will not transform your A8 into an economy car, but they can help you extract every last mile from each gallon of premium fuel, all while continuing to enjoy effortless performance. You can also see all Audi fuel economy data. For data on this model specifically, have a look at A8 MPG across all years.