22 MPG combined in a 2015 Mercedes-Benz E400 4matic won’t impress hypermilers. But realistically, E400 buyers typically aren’t prioritizing maximum MPG. This is a capable, all-weather luxury sedan with a potent turbocharged six-cylinder engine that prioritizes power and a refined driving experience over Prius-like efficiency. E400 buyers want strong performance and the prestige of Mercedes-Benz, accepting the fuel economy tradeoff.

City and highway performance

The EPA estimates the 2015 E400 4matic achieves 20 MPG in the city and 27 MPG on the highway. The city figure reflects the realities of stop-and-go traffic, where the E400’s weight and engine size affect fuel economy. However, the highway number is more respectable. The smooth-shifting seven-speed automatic transmission helps keep the engine in its most efficient range at cruising speeds, allowing relaxed long-distance travel. Don’t expect to hit 27 MPG when constantly surging past other cars, but it’s achievable when driving sensibly on relatively flat, steady-state highways.

Annual fuel cost

According to the EPA, the estimated annual fuel cost for the 2015 Mercedes-Benz E400 4matic is $2,650. This figure is based on driving 15,000 miles per year and using the EPA’s estimated combined fuel economy rating of 22 MPG. The calculation also factors in the national average fuel price, which fluctuates, so the actual cost can vary depending on location and time of fill up. Consider this number a benchmark for comparison, not a guaranteed annual expense.

Real-world expectations

While the EPA figures provide a baseline, real-world fuel economy can vary widely depending on driving style, road conditions, and maintenance. Aggressive acceleration, frequent short trips, and neglecting regular maintenance significantly impact fuel consumption. However, a smooth driving style, properly inflated tires, and timely servicing can help you get closer to the EPA estimates. The E400’s 3.0L turbocharged engine responds well to gradual inputs, so avoid jerky acceleration and hard braking.

If you drive in a hilly area, expect lower MPG. And keep in mind that using premium fuel (which is recommended) will naturally increase your overall fuel expenses.

How it compares

Compared to its rivals, the 2015 E400 4matic’s fuel economy is fairly average. A 2015 BMW 535i xDrive, with its turbocharged inline-six, achieves a similar 20 MPG city and 30 MPG highway. An Audi A6 3.0T Quattro from the same year is rated at 20 MPG city and 29 MPG highway, making it a close competitor. If lower fuel costs are important, a Lexus GS 350 AWD offers slightly better numbers — about 19 MPG city and 26 MPG highway. But those cars have different strengths and weaknesses; the buyer accepts the tradeoff for what the E400 delivers. For even more detail, you can review E400 MPG across all years. And for a broader perspective, explore all Mercedes Benz fuel economy data.

Tips to maximize efficiency

The E400 has an “ECO” mode that can mildly improve efficiency. Use it for everyday driving, particularly in stop-and-go traffic. It adjusts throttle response and shift points to prioritize fuel conservation, but it won’t drastically alter the car’s character. It’s a good tool, but not a game changer.

Ensure your tires are properly inflated to the pressure listed on the driver’s side doorjamb. Underinflated tires increase rolling resistance, which reduces fuel economy. Regularly check and adjust tire pressure, especially during seasonal temperature changes.

Avoid carrying unnecessary weight in the vehicle. The more weight the engine has to haul, the more fuel it will consume. Remove any items from the trunk or backseat that you don’t need on a regular basis. Removing the roof rack unless it’s frequently used can also have a small positive impact.

Consider using cruise control on the highway. Maintaining a consistent speed can prevent unnecessary acceleration and deceleration, which wastes fuel. However, be mindful of traffic conditions and avoid using cruise control in heavy traffic or hilly terrain.

Keep up with regular maintenance, including oil changes and air filter replacements. A well-maintained engine operates more efficiently. A dirty air filter, for instance, can restrict airflow and reduce fuel economy. Consult your owner’s manual for recommended maintenance intervals.