24 MPG combined is a reasonable compromise for the 2021 Mercedes-Benz E450 4matic All-Terrain, a vehicle that prioritizes reliable capability and refined luxury over Prius-like efficiency. This isn’t a car for hypermilers, it’s a car for affluent suburbanites who need year-round usability and appreciate the cachet of the three-pointed star, and for whom fuel costs are likely a tertiary concern at best.

City and highway performance

The E450 All-Terrain’s EPA estimates break down to 22 MPG in the city and 28 MPG on the highway. The city figure reflects the stop-and-go nature of urban driving, where the 3.0-liter inline-six’s mild-hybrid system works overtime to restart the engine and give a small boost of electric power. The highway number is more representative of steady-state cruising when the engine is at its most efficient. The nine-speed automatic transmission plays a key role, keeping the engine in its sweet spot for both acceleration and fuel conservation. Driving style dramatically affects these numbers. Lead-footed drivers can expect significantly lower mileage, especially in the city, while those with a more relaxed approach can see figures closer to the EPA estimates, and potentially even exceeding them on the highway.

Annual fuel cost

The EPA estimates an annual fuel cost of $2,400 for the 2021 Mercedes-Benz E450 4matic All-Terrain. This figure is based on driving 15,000 miles per year, with a roughly even split between city and highway driving, using the then-current national average price for premium gasoline (the recommended fuel for this engine). This is a useful benchmark for comparing running costs, but individual expenses will vary depending on driving habits, local fuel prices, and the actual miles driven. Owners who primarily drive in the city or frequently accelerate hard will likely pay more than the EPA estimate. It’s important to consider this fuel cost within the overall context of luxury car ownership, which includes higher insurance premiums, maintenance costs, and the inevitable depreciation.

Real-world expectations

While the EPA figures provide a useful baseline, real-world fuel economy depends heavily on individual driving patterns. Owners who primarily commute in congested urban areas will likely see figures closer to the city MPG estimate (around 22 MPG), while those who frequently embark on long highway journeys can reasonably expect numbers closer to the 28 MPG highway rating. Some owners on enthusiast forums have reported exceeding the highway estimate on long trips with minimal stop-and-go traffic, achieving upwards of 30 MPG. However, aggressive driving, frequent use of the sport modes (which alter the transmission mapping and throttle response), and carrying heavy loads will all negatively impact fuel efficiency. All-wheel drive also adds weight. The E450 4matic owner isn’t typically obsessing over fuel mileage, they are more interested in the sure-footedness this vehicle provides in inclement weather.

How it compares

The E450 All-Terrain’s fuel economy sits squarely within the expected range for its class. The Volvo V90 Cross Country, another all-wheel-drive luxury wagon, achieves an EPA-estimated 22 MPG combined using its turbocharged and supercharged four-cylinder engine. The Audi A6 allroad, a direct competitor, manages a similar 23 MPG combined. The smaller BMW 330i xDrive wagon fares better, with an EPA combined rating of 28 MPG, but sacrifices space and outright performance. The Porsche Panamera Sport Turismo, with its broader range of engine options, offers models both more and less efficient than the E450, depending on the specific configuration. For shoppers considering an SUV instead, the Mercedes-Benz GLE 450 4matic, which uses a similar mild-hybrid inline-six engine, is rated at 22 MPG combined. These comparisons highlight that the E450 All-Terrain offers fuel economy that’s competitive within its segment, considering its blend of power, all-weather capability, and passenger/cargo space. E450 MPG across all years is relatively consistent.

Tips to maximize efficiency

Take advantage of the E450 All-Terrain’s Eco driving mode. This setting optimizes the transmission for fuel efficiency, encouraging earlier upshifts and more relaxed throttle mapping. It dulls the responsiveness, but if maximizing your MPG is the goal, this is a great method.

Ensure your tires are properly inflated. Underinflated tires increase rolling resistance, which directly impacts fuel consumption. Check your tire pressure regularly and maintain the recommended levels specified on the doorjamb sticker.

Minimize idling. Modern engines are remarkably efficient when running, but idling consumes fuel without covering any distance. Avoid letting the engine idle for extended periods, especially in stop-and-go traffic. Consider turning off the engine completely if you anticipate being stationary for more than a minute or two.

Use cruise control on the highway. Maintaining a consistent speed minimizes unnecessary acceleration and deceleration, which can significantly improve fuel economy on long drives. Use the adaptive cruise control system for even greater efficiency and convenience.

Lighten your load. Carrying unnecessary weight increases fuel consumption. Remove any non-essential items from the vehicle, particularly heavy objects in the trunk or cargo area. The less the engine has to work, the better your MPG will be. You can view all Mercedes Benz fuel economy data for more ideas on improving efficiency.