20 MPG combined isn’t going to win any awards, but the 2015 Mercedes-Benz S550 occupies a unique space in the full-size luxury sedan class. It’s about effortless power, opulent features, and a driving experience that suggests success. This level of refinement requires a certain amount of fuel. The S550 buyer isn’t cross-shopping against a Prius; they’re weighing luxury against capability and presence.

City and highway performance

The EPA estimates the 2015 S550 will achieve 17 MPG in the city and 26 MPG on the highway. The city figure reflects the engine’s increased workload in stop-and-go traffic, where the 4.7L V8 has to repeatedly accelerate a large vehicle. The 26 MPG highway rating is more respectable, showcasing the engine’s ability to cruise efficiently when coupled with the smooth-shifting seven-speed automatic transmission. The S550 is designed for long-distance travel, its air suspension and supremely comfortable seats encouraging extended journeys. The car shines on highway miles, and the fuel economy reflects that.

Annual fuel cost

The EPA estimates the annual fuel cost for the 2015 Mercedes-Benz S550 at $2,900. This calculation is based on driving 15,000 miles per year and using national average fuel prices. Individual costs will vary depending on driving habits, location, and fuel prices, but this provides a benchmark for potential owners. For the typical S550 buyer, this figure is unlikely to be a significant deterrent, viewed as a cost of ownership associated with this class of vehicle.

Real-world expectations

EPA estimates provide a standardized benchmark, but real-world fuel economy often varies. Aggressive driving, frequent short trips, and prolonged idling can all reduce fuel efficiency. Conversely, careful driving, proper maintenance, and consistent highway cruising can improve upon the EPA estimates. The S550 has technologies designed to improve fuel economy, such as ECO start/stop, which shuts off the engine at idle, and a transmission that optimizes gear selection for efficiency. Ultimately, the driver’s behavior has the biggest impact.

How it compares

The 2015 S550 has reasonable fuel economy compared to its competitors. For example, the 2015 BMW 750i xDrive, with its 4.4L V8, achieves an EPA-estimated 16 MPG city and 25 MPG highway. The Audi A8 4.0T, with its similar displacement V8, yields around 18 MPG city and 28 MPG highway. A similarly equipped Lexus LS 460 might offer slightly better numbers, hovering around 19 city and 27 highway. The S550 prioritizes an effortless and comfortable driving experience, and its fuel economy reflects that choice. For those concerned about fuel consumption, examining S550 MPG across all years may reveal options that meet specific needs.

Tips to maximize efficiency

Use the ECO start/stop feature. Consistently allowing the engine to shut off at stoplights and in traffic can reduce fuel consumption over time, particularly in city driving. It’s a free and readily available feature, engineered for real-world driving scenarios.

Monitor tire pressure regularly. Underinflated tires create more rolling resistance, forcing the engine to work harder and consume more fuel. The S550 has a tire pressure monitoring system (TPMS), making it easy to stay informed. Keeping the tires properly inflated to the recommended pressure ensures optimal fuel efficiency and handling.

Avoid aggressive acceleration. The S550’s V8 engine is responsive, but rapid acceleration consumes significantly more fuel than gradual acceleration. Anticipate traffic flow and accelerate smoothly, minimizing unnecessary bursts of power. This approach improves fuel economy and creates a relaxed driving experience.

Schedule regular maintenance. A well-maintained engine operates more efficiently. Follow the manufacturer’s recommended maintenance schedule, including oil changes, air filter replacements, and spark plug inspections. These tasks can prevent performance degradation and maintain optimal fuel economy. Owners can find all Mercedes Benz fuel economy data with simple searches online.

Use cruise control on the highway. Maintaining a consistent speed on the highway minimizes unnecessary acceleration and deceleration, which can improve fuel economy. Engaging cruise control allows the engine to operate at a more constant load, optimizing efficiency. Just be sure to disengage when traffic conditions warrant.