15 MPG combined in the 2026 Mercedes-Benz GLS600 4MATIC Maybach 4.0L 8-cylinder isn’t just a number; it’s a declaration of intent, an acknowledgment that for certain buyers, efficiency is secondary to an unparalleled experience of opulent power and quiet isolation. This isn’t a vehicle designed to sip fuel; it’s engineered to command the road with effortless grace, its 550 horsepower V8 delivering immediate, authoritative thrust on demand. The owner of a GLS600 Maybach understands that this level of luxury, performance, and craftsmanship comes with a certain thermodynamic reality. They prioritize the quiet cabin, the exquisite materials, and the confidence of that potent 4.0-liter twin-turbo heart over incremental fuel savings. For them, the journey is not merely about reaching a destination, but how they arrive, cocooned in a sanctuary of ultimate refinement.

City and highway performance

Looking at the specifics, the GLS600 Maybach’s 13 MPG city rating paints an expected picture for a vehicle of its stature, weight, and powertrain. Navigating urban environments, with their stop-and-go traffic and frequent accelerations, demands significant energy from the 4.0L V8. The mild-hybrid EQ Boost system, while offering a subtle assist off the line and improving start/stop functionality, can only do so much against more than 6,000 pounds of meticulously crafted luxury. This isn’t a deficit; it’s a characteristic. The effortless torque delivery, the smooth engagement of the 9-speed automatic transmission, and the hushed cabin make city driving surprisingly unstressed, even as the fuel gauge subtly nudges downward. On the highway, the GLS600 Maybach improves to 18 MPG. This figure reflects the efficiency gains when the large V8 can settle into a steady cruising rhythm. At highway speeds, the aerodynamic profiling, the advanced transmission’s ability to find the optimal gear, and the inherent efficiency of a well-engineered eight-cylinder engine at part-throttle all contribute. Long-distance comfort is important for this vehicle, and while 18 MPG isn’t class-leading, it allows for substantial cruising ranges between refills, ensuring journeys remain uninterrupted and supremely comfortable.

Annual fuel cost

The EPA estimates an annual fuel cost of $3,850 for the 2026 Mercedes-Benz GLS600 4MATIC Maybach. This figure is calculated based on an assumption of 15,000 miles driven per year, split between city and highway driving, using national average fuel prices. For a vehicle demanding premium fuel and delivering 15 MPG combined, this cost is a clear representation of its operational expense. Owners of the GLS600 Maybach are typically not deterred by this figure. The total cost of ownership for such a vehicle includes significant depreciation, insurance, and maintenance, making the annual fuel expense a relatively minor component of their overall automotive budget. Instead, they view it as a necessary expenditure for the privilege of experiencing the vehicle’s unique blend of power, prestige, and unparalleled comfort. The focus is on the journey, the status, and the sheer capability, not on penny-pinching at the pump.

Real-world expectations

In real-world driving, the 2026 GLS600 Maybach’s fuel economy can fluctuate. Aggressive driving, particularly frequent use of the powerful V8 for swift acceleration, will naturally pull the numbers closer to, or even below, the 13 MPG city rating. The smooth nature of the power delivery can easily tempt drivers to exploit the engine’s capabilities. Conversely, a disciplined and smooth driving style, especially on long highway cruises using intelligent cruise control and maintaining consistent speeds, might see figures occasionally nudge slightly above the EPA estimates. Environmental factors like extremely cold weather, heavy winds, or driving at high altitudes can also impact efficiency. Load, be it passengers, luggage, or accessories like roof racks (though less common on a Maybach), adds weight and resistance, further influencing fuel consumption. The owner of a GLS600 Maybach expects superlative performance and comfort, and the real-world fuel economy is simply a byproduct of delivering that experience. They understand that such a magnificent machine requires commensurate input to maintain its majestic forward momentum.

How it compares

While the GLS600 Maybach occupies a rarefied segment, its fuel economy can be benchmarked against other ultra-luxury and high-performance SUVs. For instance, the Bentley Bentayga Speed, with its more potent W12 engine, typically achieves a combined 15 MPG, mirroring the Maybach’s figure despite its larger engine. A Rolls-Royce Cullinan, with its 6.75L V12, also typically delivers a comparable 14-16 MPG combined. Moving to more performance-oriented but still luxurious rivals, a BMW X7 M60i (which shares a similar 4.4L twin-turbo V8 to the GLS600’s engine family) often sees 18 MPG combined, reflecting its slightly lighter weight and more performance-focused tuning. Even a strong competitor like the top-tier Range Rover SV, with its 4.4L twin-turbo V8, generally achieves around 18 MPG combined. These comparisons highlight that the GLS600 Maybach’s 15 MPG combined is right in line with the expectations for this exclusive class of vehicle. Owners aren’t cross-shopping with hybrid crossovers; they are weighing the pinnacle of luxury, presence, and performance. The fuel economy is merely a characteristic of the chosen powertrain and the grand scale of the vehicle, not a decisive factor when considering these ultimate expressions of automotive indulgence. For a complete look at this model’s efficiency across all variants, explore GLS600 MPG across all years, and to review data for other vehicles from the marque, see all Mercedes Benz fuel economy data.

Tips to maximize efficiency

Even in a vehicle where fuel economy is not the primary concern, certain driving habits can subtly improve efficiency. Use the ECO driving mode, if available, which will adjust throttle response and transmission shift points for more economical operation, without significantly compromising the Maybach’s refined character.

Maintain consistent speeds on highways. The GLS600’s adaptive cruise control is exceptionally smooth and can help avoid unnecessary acceleration and braking, which are major contributors to fuel consumption in heavy vehicles.

Ensure correct tire pressure. Properly inflated tires reduce rolling resistance, which can lead to measurable improvements in fuel economy, and it’s also critical for safety and tire longevity.

Anticipate traffic flow. Smooth, gradual acceleration and braking use less fuel than abrupt maneuvers. Given the GLS600’s commanding view and excellent visibility, planning ahead for lights and stops is made easier.

Minimize unnecessary weight. While not usually a major factor for Maybach owners, removing any heavy, non-essential items from the trunk can marginally lighten the load and improve efficiency over time.