22 MPG combined isn’t going to win any hypermiling contests, but it’s a perfectly acceptable figure for the 2020 Mercedes-Benz S450 4matic. This isn’t a car purchased for its frugality. It’s a flagship sedan, a statement of success, and a mobile office for executives who prioritize comfort, technology, and prestige above all else. Fuel economy plays a role, but it’s far down the list compared to arriving refreshed and in style.

City and highway performance

The EPA estimates the S450 4matic achieves 18 MPG in the city and 28 MPG on the highway. The city figure reflects the reality of stop-and-go traffic, where the car’s weight and the engine’s need to overcome inertia take their toll. The highway number is more flattering, showcasing the effectiveness of the 9-speed automatic transmission and the engine’s ability to cruise efficiently at higher speeds. The 3.0L inline-six benefits from turbocharging and mild hybrid technology, which aids in both performance and efficiency. Don’t expect Prius-like numbers in urban environments, but anticipate decent long-distance economy.

Annual fuel cost

The EPA estimates the annual fuel cost for the 2020 Mercedes-Benz S450 4matic at $2,650. This is based on driving 15,000 miles per year and using national average fuel prices. Naturally, your actual fuel cost will vary depending on your driving habits, the type of fuel you use (premium is recommended), and local fuel prices. However, this $2,650 figure provides a useful baseline for comparing the S450’s fuel expenses to other vehicles in its class.

Real-world expectations

While the EPA provides a standardized testing protocol, real-world fuel economy often deviates. Aggressive driving, frequent short trips, and prolonged idling can significantly reduce MPG. Conversely, gentle acceleration, consistent highway speeds, and proper tire inflation can improve efficiency. Owners report a range of MPG figures, but most align with the EPA’s estimates, particularly on longer trips. The S450’s turbocharged engine with electric motor and features like “Eco” mode can help optimize fuel consumption if used judiciously.

How it compares

The fuel economy of the 2020 S450 4matic is within the expected range for its class. The BMW 740i xDrive, for example, also powered by a 3.0L inline-six, posts EPA ratings of 22 MPG combined, 20 city, and 29 highway. The Audi A8 3.0T quattro achieves 21 MPG combined, 19 city, and 28 highway. These subtle differences are unlikely to sway a buyer already drawn to the S450’s specific blend of luxury and brand cachet. For shoppers considering alternatives, the Lexus LS 500h hybrid offers significantly better fuel economy, around 25 MPG combined, but at the expense of some performance and a different driving experience. Buyers can compare S450 MPG across all years and see how this model performs.

Tips to maximize efficiency

Use the car’s “Eco” mode. It adjusts throttle response, transmission mapping, and climate control settings to prioritize fuel efficiency. While it might slightly reduce performance, it can make a noticeable difference, particularly in city driving. Understand all Mercedes Benz fuel economy data to see how the lineup is evolving.

Maintain proper tire inflation. Underinflated tires increase rolling resistance, which reduces fuel economy. Check your tire pressure regularly and inflate to the recommended levels, which can be found on a sticker inside the driver’s side doorjamb.

Anticipate traffic flow and avoid aggressive acceleration and braking. Smooth, consistent driving is the key to maximizing fuel efficiency. Give yourself plenty of following distance, and try to maintain a steady speed whenever possible. Let momentum work for you, not against you.

Minimize idling time. If you’re stopped for more than a minute or two, turn off the engine. Modern engines are designed to restart quickly and efficiently, and idling consumes fuel without covering any distance. Consider this particularly when waiting to pick someone up or sitting in a traffic jam.

Consider removing unnecessary weight from the vehicle. Extra weight increases fuel consumption, so remove any items from the trunk or backseat that you don’t need to carry. This could include golf clubs, extra luggage, or other heavy objects that are simply adding to the car’s overall mass and requiring more energy to move.