22 MPG combined isn’t the primary reason someone buys a 2018 Mercedes-Benz S450. It’s a supremely comfortable, technologically advanced, and effortlessly powerful luxury sedan. Owners prioritize a quiet driving experience and a prestigious image over maximizing fuel efficiency. While not the worst in its class, the S450’s fuel economy is average, a fact accepted by those who purchase this flagship vehicle.

City and highway performance

The EPA estimates the S450 will achieve 19 MPG in the city and 28 MPG on the highway. The city figure reflects typical stop-and-go driving, where the S450’s strong 3.0L turbocharged six-cylinder engine must work harder. The highway figure showcases the benefits of the S450’s aerodynamic design and smooth-shifting 9-speed automatic transmission, allowing it to cruise efficiently at higher speeds. These numbers mean fewer stops at the gas station on long trips compared to around-town errands.

Annual fuel cost

The EPA estimates the annual fuel cost for the 2018 Mercedes-Benz S450 at $2,650. This is based on driving 15,000 miles per year and using the national average fuel price for premium gasoline. Your actual fuel costs may vary depending on your driving habits, the type of fuel you use, and local fuel prices. For example, drivers who spend a lot of time in heavy traffic or drive aggressively are likely to see a higher annual fuel bill. The EPA offers more information about these calculations on their website.

Real-world expectations

EPA estimates provide a good baseline, but real-world fuel economy often differs. Expect slight variations based on driving style, terrain, and weather. Aggressive acceleration and frequent hard braking will decrease fuel efficiency, while smooth and steady driving can help you reach or exceed the EPA numbers, especially on the highway. Properly maintained tires, using the correct grade of premium fuel, and avoiding excessive idling also help to improve fuel economy. Many owners report figures close to the EPA estimates, confirming the S450 can achieve reasonable MPG when driven carefully.

How it compares

The S450’s fuel economy is similar to other luxury sedans in its class, but there are differences. The BMW 740i, with its similar 3.0L turbocharged inline-six, achieves a slightly better 25 MPG combined. The Audi A8, another competitor, offers similar fuel economy. Meanwhile, the Lexus LS 500 offers a similar level of luxury, but its V6 engine delivers comparable fuel economy at around 22 MPG combined. The Porsche Panamera, with its optional V6, is another sporty alternative within the same fuel economy range. Potential buyers often weigh these MPG figures against other factors like performance, technology, and brand prestige. For those seeking better efficiency, a hybrid alternative like the LS 500h offers superior fuel economy but sacrifices some cargo space. Compare all Mercedes Benz fuel economy data to see where the S450 falls within its own brand, and you can also review the S450 MPG across all years.

Tips to maximize efficiency

The S450’s 9-speed automatic transmission is designed for efficiency, so use it. Gentle acceleration allows the transmission to upshift smoothly and keep the engine in its most efficient RPM range. Avoid aggressive launches and unnecessary downshifts.

Tire pressure is important for fuel economy. Regularly check your tire pressure and ensure it’s inflated to the recommended levels. Underinflated tires increase rolling resistance, forcing the engine to work harder and consume more fuel. Properly inflated tires can improve fuel efficiency by as much as 3%.

The S450 has driving modes, including an “ECO” mode. Selecting this mode optimizes vehicle systems for fuel efficiency, such as throttle response and shift points. While it may slightly reduce performance, it can improve your MPG, especially in city driving.

Remove unnecessary weight from the vehicle. Remove items you don’t need from the trunk, as extra weight requires more energy to accelerate and maintain speed. Even small amounts of weight can impact fuel economy over time, so decluttering your S450 can pay off.

Plan your routes to avoid congested areas and stop-and-go traffic. Idling consumes fuel without covering any distance, so minimizing idling time can improve your MPG. Use navigation apps to find the most efficient routes and avoid traffic jams.