18 MPG combined isn’t going to win any awards for less gas, but it properly contextualizes the 2018 Audi S8 4.0L 8-cyl. This isn’t an economy car. It’s a high-performance luxury sedan designed to deliver thrilling acceleration and a supremely comfortable ride for those who prioritize driving experience above all else. Fuel economy is a secondary concern, a necessary compromise for the power and prestige that the S8 offers.

City and highway performance

The EPA estimates suggest 14 MPG in the city and 24 MPG on the highway. That city figure reflects the reality of stop-and-go traffic, where the S8’s hefty curb weight and powerful engine demand more fuel. The highway number is more palatable, showcasing the advantage of the automatic transmission and its ability to settle into a more efficient cruising speed. The 4.0L V8 is truly in its element on the open road, offering effortless passing power while consuming a reasonable amount of fuel, relative to its staggering output. While the highway figure may seem respectable, understand that frequent bursts of acceleration or sustained high-speed driving will drag that number down quickly.

Annual fuel cost

The EPA estimates the annual fuel cost for the 2018 Audi S8 4.0L 8-cyl at $3,200. This figure is based on driving 15,000 miles per year, with a roughly 55/45 split between city and highway driving, using the national average fuel price when the estimate was calculated. Your actual fuel costs will vary depending on your driving habits and local fuel prices. For example, if you primarily drive in the city or have a lead foot, expect to exceed that $3,200 figure significantly. If you primarily drive on the highway and are gentle with the throttle, you might get it slightly below that mark. The $3,200 annual fuel cost should be a wake-up call for potential buyers to realize this is no ordinary daily driver.

Real-world expectations

Real-world fuel economy for the 2018 Audi S8 often mirrors the EPA estimates, but expect some deviation based on driving style and conditions. Drivers who frequently exploit the S8’s performance potential will likely see lower numbers, especially in the city. Highway numbers are more consistently achievable, assuming moderate speeds and minimal aggressive driving. The S8’s advanced technology, including its adaptive air suspension and quattro all-wheel drive, also contribute to fuel consumption. These systems enhance the driving experience but aren’t designed to maximize efficiency. Head over to FuelEconomyHub to view the S8 MPG across all years.

How it compares

Compared to its competitors, the 2018 Audi S8’s fuel economy is typical for its class. For example, the 2018 BMW M5 with its 4.4L V8 achieves around 17 MPG combined, a very similar figure. The Mercedes-AMG S63 of the same year, also packing a powerful V8, sits in the same ballpark at around 19 MPG combined. The Porsche Panamera Turbo, while offering slightly better handling, returns roughly the same 18 MPG combined, maybe 1 MPG more optimistic. The slight variances in MPG figures are often negligible in the real world and are hardly the decisive factor for buyers in this segment. These buyers prioritize performance, luxury, and technology over minor fuel savings. For comparisons across the entire product line, view all Audi fuel economy data.

Tips to maximize efficiency

Gentle acceleration makes a noticeable difference. The S8’s engine is responsive, meaning you don’t need to bury your foot in the throttle to get moving. Smooth, gradual acceleration will minimize fuel consumption, especially in city driving. Avoiding unnecessary hard launches and aggressive passing maneuvers will also pay dividends at the pump.

Maintain a consistent speed on the highway. Using cruise control, especially on long drives, can help you maintain a more consistent speed, which translates to better fuel economy. Varying your speed frequently requires more energy and, therefore, more fuel. Be aware of your speed overall, exceeding the speed limit impacts fuel economy exponentially at higher velocities.

Keep your tires properly inflated. Underinflated tires increase rolling resistance, forcing the engine to work harder and consume more fuel. Check your tire pressure regularly and inflate them to the recommended pressure listed on the sticker inside the driver’s side door. Even a few PSI of difference can noticeably impact fuel economy on a heavy car like the S8.

Minimize idling time. Letting the engine idle for extended periods, whether waiting in a parking lot or warming it up on a cold morning, wastes fuel. Turn off the engine if you anticipate idling for more than a minute. Modern engines don’t require the extended warm-up periods that older engines did.

Remove excess weight from the vehicle. While the impact of removing a few small items might seem minimal, extra weight adds up. Remove any unnecessary items from the trunk or backseat to reduce the overall weight of the vehicle causing increased fuel consumption. Less weight translates to less work for the engine and, consequently, better fuel efficiency.