The 2019 Mercedes-Benz S450 4MATIC’s 22 MPG combined isn’t its strongest selling point, but it’s important to consider the bigger picture. This is a flagship sedan, engineered for exceptional comfort, cutting-edge technology, and effortless performance. Fuel economy, while still relevant, is a lower priority for most S-Class buyers. They prioritize a quiet driving experience and ample power over maximizing every mile per gallon.

City and highway performance

The EPA estimates 18 MPG in the city and 28 MPG on the highway for the S450 equipped with the 3.0L inline-six and 4MATIC all-wheel drive. The city number reflects the reality of stop-and-go traffic, where the car’s weight and the engine’s thirst are more noticeable. The highway figure is more appealing, showcasing the benefits of the smooth-shifting 9-speed automatic transmission and the engine’s ability to cruise easily at higher speeds. Owners who drive mostly on the open road will likely see figures close to, or even slightly exceeding, the EPA’s estimate.

Annual fuel cost

The EPA calculates an annual fuel cost of $2,650 for the 2019 Mercedes-Benz S450 4MATIC. This figure is based on driving 15,000 miles per year, using a national average fuel price. Remember that this is an average, and your actual fuel costs may vary depending on your driving habits, the type of fuel you use, and local fuel prices. Someone who drives mainly in the city, drives aggressively, or lives in an area with high fuel costs will undoubtedly spend more.

Real-world expectations

While EPA estimates provide a standardized baseline, real-world fuel economy often differs. S450 owners report figures that vary based on driving style and conditions. Expect the combined MPG to be around the low 20s for most drivers. Highway trips at consistent speeds should yield numbers in the mid-to-high 20s, while city driving can easily dip below the EPA’s 18 MPG estimate. Aggressive acceleration, frequent short trips, and heavy traffic all contribute to lower fuel economy.

How it compares

Compared to its competitors, the S450’s fuel economy is similar to others in its class. The BMW 740i, with its 3.0L inline-six, achieves similar EPA ratings. The Audi A8, with its comparable engine, also offers similar figures, reflecting the inherent compromises between performance, luxury, and efficiency in this class. For a more direct comparison, you can explore S450 MPG across all years. Buyers considering the plug-in hybrid S560e will see a significant increase in fuel economy, particularly in city driving, and it offers the option of electric-only propulsion for short distances. The Lexus LS 500, known for its reliability, delivers around 22 MPG combined, so the S450 buyer is unlikely to switch to Lexus based on fuel economy alone. A potential customer might, however, compare all Mercedes Benz fuel economy data before deciding on a final model.

Tips to maximize efficiency

The S450’s 3.0L inline-six is a smooth and responsive engine, but it still benefits from careful driving. Avoid aggressive acceleration and hard braking, as these actions consume significantly more fuel. A smooth, steady driving style will allow the engine to operate more efficiently.

Ensure your tires are properly inflated. Underinflated tires increase rolling resistance, which reduces fuel economy. Check your tire pressure regularly and maintain the recommended pressure listed on the doorjamb sticker.

The S450 features various driving modes. Experiment with “Comfort” or “Eco” mode, which adjust throttle response and transmission mapping to prioritize fuel efficiency. These modes may slightly reduce performance, but they can make a noticeable difference in fuel consumption, especially during city driving.

Minimize idling. If you anticipate stopping for more than a minute, turn off the engine. Modern engines are designed to restart quickly and efficiently, and idling consumes fuel without moving the car. This is especially important in urban environments.

Reduce unnecessary weight. Carrying extra cargo increases the vehicle’s weight, which reduces fuel economy. Remove any items from the trunk or passenger compartment that are not essential. Every pound counts, especially in city driving.