25 MPG combined is an acceptable, if unspectacular, number for the 2015 Mercedes-Benz E400 Hybrid. The E400 Hybrid isn’t bought for its fuel sipping ability; it’s bought for its smooth, effortless power delivery and the cachet of driving a Mercedes-Benz E-Class. This is a car for those who value refinement and comfort above all else, and see the mild hybrid system as a way to enhance those qualities, not just chase MPGs.

City and highway performance

The EPA estimates of 24 MPG in the city and 28 MPG on the highway paint a clear picture. This is not a car that will dramatically outperform its ratings in real-world driving. The electrically-assisted 3.5L V6 works well in urban environments, recapturing energy during braking and providing a small boost of electric torque for smoother acceleration. On the highway, the E400 Hybrid settles into a comfortable cruise, but the hybrid system’s benefits are less obvious at higher speeds. Expect the highway figure to match, not exceed, the EPA’s 28 MPG rating, especially on spirited road trips.

Annual fuel cost

The EPA estimates an annual fuel cost of $2,300 for the 2015 Mercedes-Benz E400 Hybrid. This figure is calculated based on driving 15,000 miles per year and using national average fuel prices. This is an important number to consider, not just in absolute terms, but relative to other vehicles in the luxury sedan class. While fuel prices fluctuate, you can use this figure as a benchmark when comparing the E400 Hybrid’s running costs against its competitors. The EPA estimates also assume a certain percentage of city versus highway driving, which may or may not match your usage patterns.

Real-world expectations

While the EPA ratings provide a useful baseline, real-world fuel economy will always vary. Drivers in urban environments with heavy traffic will likely see figures closer to the 24 MPG city rating, while those who frequently undertake longer highway journeys may approach, but rarely exceed, the 28 MPG highway figure. Driving style plays a significant role; aggressive acceleration and braking will negatively impact the hybrid system’s efficiency.

How it compares

In 2015, the E400 Hybrid occupied a unique position in the market. A similarly equipped gasoline-only E350, for example, was rated at 20 MPG city and 29 MPG highway. A BMW 535i, known for its performance, achieved around 20 MPG city and 30 MPG highway. The Lexus GS 450h, a more dedicated hybrid offering, boasted ratings of 29 MPG city and 34 MPG highway. These comparisons showcase the E400 Hybrid’s compromise: it offered some fuel savings over a standard V6 E-Class, but didn’t reach the fuel efficiency of more focused hybrid models. Those seeking maximum fuel efficiency within the Mercedes Benz lineup should explore all Mercedes Benz fuel economy data. For specific information on E400 MPG across all years check out our dedicated model page.

Tips to maximize efficiency

Use the car’s “ECO” mode. This setting optimizes throttle response, transmission shift points, and climate control to prioritize fuel efficiency. It’s not a massive change, but over time it can contribute to noticeable savings. Get to know the system and how it works.

Gentle acceleration is key when using the electric motor. The E400 Hybrid features an electric motor that assists the gasoline engine. Avoid aggressive acceleration, especially from a standstill, to keep the car running on electric power for as long as possible. Watch the gauge in the instrument panel that indicates when the electric motor is assisting, and try to stay in that zone.

Pay attention to tire pressure. Regularly check and maintain the correct tire pressure, as specified on the doorjamb sticker. Underinflated tires increase rolling resistance, which reduces fuel economy. This is a simple one that helps.

Minimize aerodynamic drag. Remove any unnecessary roof racks, cargo carriers, or other accessories that add drag. The E-Class is already a relatively aerodynamic car, but anything you can do to smooth airflow will help, especially on the highway. Make sure everything is tight.