23 MPG combined is a reasonable, if unremarkable, figure for the 2015 Mercedes-Benz E400 with its smooth, turbocharged 3.0L V6. That number doesn’t tell you about the effortless performance and premium experience that the E400 delivers. This isn’t a car purchased solely, or even primarily, for its fuel efficiency. It’s chosen by those who prioritize responsive power, refined handling, and the prestige of the Mercedes-Benz badge. They are willing to accept average fuel economy in exchange for the E400’s other considerable virtues.

City and highway performance

The EPA estimates the E400 at 20 MPG in the city and 29 MPG on the highway. These numbers reflect how the car performs in different driving environments. City driving, with its constant stop-and-go traffic, tends to penalize turbocharged engines more than naturally aspirated ones.

The turbo needs time to spool up after each stop, leading to lower fuel economy compared to consistent highway speeds. The E400’s 7-speed automatic transmission helps it cruise comfortably on the highway, keeping the engine at its most efficient, resulting in the better number. Consider these figures as a relative guide, rather than an absolute promise. Your actual mileage will vary based on driving style and traffic conditions.

Annual fuel cost

The EPA estimates the annual fuel cost for the 2015 Mercedes-Benz E400 at exactly $2,500. This figure is based on driving 15,000 miles per year, using the EPA’s estimated combined fuel economy, and assuming the national average fuel price. Remember that fuel prices fluctuate, and your personal mileage may differ from the EPA’s estimates.

Owners who drive fewer miles annually will naturally spend less on fuel, those who spend most of their time in stop-and-go city traffic might see that $2,500 figure climb higher. It is one data point to consider as you review all Mercedes Benz fuel economy data.

Real-world expectations

While the EPA provides a standardized benchmark, real-world fuel economy often differs. E400 owners frequently report figures that are slightly lower than the EPA’s city estimate, especially in congested urban areas.

Highway mileage can often meet or even exceed the 29 MPG rating, particularly on longer road trips. Aggressive driving, frequent short trips, and consistently engaging the sport mode will all negatively impact fuel consumption. A gentle driving style and careful route planning can help you approach the EPA’s figures, which are helpful in evaluating E400 MPG across all years.

How it compares

The 2015 E400’s fuel economy places it in a competitive, but not class-leading, position. Consider its rivals. The BMW 535i, with its similarly powerful 3.0L turbocharged inline-six, offers comparable fuel economy around 22 MPG combined. The Audi A6 3.0T, another strong contender, achieves a similar 21 MPG combined. For buyers considering fuel efficiency as a primary factor, the Lexus GS 350 (around 23 MPG combined) presents a slightly more efficient alternative, if one less focused on high performance feel. The Volvo S60 T6 Drive-E offered a markedly better combined MPG of 28 but for a very different driving experience. The E400 buyer, however, is often willing to trade a few MPG for the Mercedes-Benz driving experience, brand cachet, and the distinct character of the car.

Tips to maximize efficiency

Avoid aggressive acceleration and braking. The E400’s turbocharged engine responds well to a gentle foot. Try to anticipate traffic flow and maintain a consistent speed whenever possible. Quick bursts of speed followed by hard braking will burn through significantly more fuel.

Regular maintenance is critical for optimal fuel economy. Ensure that your tires are properly inflated, and that the engine air filter is clean. A well-maintained engine operates more efficiently, consuming less fuel. Follow the manufacturer’s recommended service schedule.

Use the E400’s “Eco” driving mode when conditions allow. This mode adjusts the throttle response and transmission shift points to prioritize fuel efficiency. It may slightly reduce performance, but it can make a noticeable difference on longer journeys.

Reduce unnecessary weight. Carrying extra cargo in the trunk adds to the vehicle’s overall weight, forcing the engine to work harder and consume more fuel. Remove any items that you don’t need on a regular basis.

Plan your routes carefully. Avoid congested areas and roads with frequent stoplights whenever possible. Even a small reduction in stop-and-go driving can significantly improve your fuel economy.