21 MPG combined. No one shopping for a 2018 Mercedes-Benz E400 4matic wagon is prioritizing ultimate fuel efficiency. People interested in this version, with its smooth 3.0L turbo inline-six, the sure-footed 4matic all-wheel-drive, and the increasingly rare station wagon body style, are looking for a specific mix of performance, practicality, and luxury. Fuel economy is likely lower on the list than cargo capacity, easy acceleration, and a prestigious brand.

City and highway performance

The EPA estimates 19 MPG in the city and 25 MPG on the highway. These numbers reflect the E400 4matic wagon’s weight (over 4,300 lbs) and the demands on its engine. The turbocharged six-cylinder, while smooth and responsive, needs to work to move this heavy vehicle, especially in stop-and-go city driving. The nine-speed automatic transmission tries to help by quickly shifting to higher gears, but city driving means lower fuel efficiency. On the open road, the E400 4matic wagon cruises more easily, helped by its aerodynamic shape and taller gear ratios, improving highway MPG.

Annual fuel cost

The EPA estimates the annual fuel cost for the 2018 Mercedes-Benz E400 4matic wagon at $2,750. This assumes 15,000 miles of driving per year, with a mix of city and highway conditions, using the national average fuel price. It is a useful comparison point, but individual fuel costs will vary based on driving habits, local fuel prices, and the proportion of city to highway miles driven. Consider your driving patterns when estimating your potential fuel expenses.

Real-world expectations

The EPA provides a standard, but real-world fuel economy often differs. Hard acceleration, frequent short trips, and long idling can all hurt MPG. Many owners report getting numbers close to the EPA estimates during mixed driving, and some do better than the highway MPG rating on long trips with consistent speeds. But city drivers with a lead foot may see their average MPG drop below the 19 MPG city estimate. The E400 4Matic wagon’s all-wheel-drive system will also reduce MPG compared to a rear-wheel-drive E-Class sedan.

How it compares

The 2018 Mercedes-Benz E400 4matic wagon has few competitors in the luxury station wagon market. The Volvo V90 T6 AWD, for example, gets a combined 25 MPG with its supercharged and turbocharged four-cylinder engine, making it more efficient than the E400. But some buyers will prefer the Mercedes’ inline-six for its smoother power and engine sound. An Audi A6 allroad from around the same time (though the allroad has a higher ride height) offers similar fuel economy to the Volvo. Those considering all Mercedes Benz fuel economy data might also consider the GLC 300 SUV, which delivers slightly better MPG but lacks the E400 wagon’s space and sporty feel. Review E400 MPG across all years to see if an earlier model might work for you. The E400’s buyer values the wagon body, the turbo-six’s character, and the E-Class feel more than ultimate fuel efficiency.

Tips to maximize efficiency

Use the E400 4matic’s drive mode selector. “Comfort” or “Eco” mode will change the throttle response and transmission shift points to prioritize fuel efficiency over performance, especially in city driving. This can change MPG, but expect less aggressive acceleration when you need it.

Keep tires properly inflated. Under-inflated tires increase rolling resistance, making the engine work harder and burn more fuel. Check your tire pressures often and inflate them to the recommended levels on the driver’s side doorjamb.

Avoid idling. Letting the engine idle burns fuel without going anywhere. If you’re stopped for more than a minute or two, turn off the engine. Cars don’t need long warm-up periods, so you can drive gently soon after starting.

Reduce weight. Extra weight in the car can reduce fuel economy. Remove items you don’t need from the cargo area and passenger area, because even small weight adds up.

Plan routes. Avoiding traffic and stop-and-go areas can greatly improve fuel economy. Use navigation apps to find efficient routes, even if they’re longer. Consistent speed and less braking help MPG.