17 miles per gallon combined for the 2026 Mercedes-Benz AMG GLS63 4matic Plus 4.0L 8-cyl. is a number that, in isolation, might cause some to raise an eyebrow. But for an individual considering an AMG GLS63, it’s less a red flag and more a confirmation of inherent character. This is a high-performance machine wrapped in an opulent, family-friendly package, an automotive statement of intent. The target demographic for the AMG GLS63 knows the power and presence they’re commanding, and they accept that such attributes come with commensurate fuel consumption. They are individuals who demand the ultimate blend of executive-class comfort, three-row utility, and supercar-rivaling acceleration. The 17 MPG figure tells them precisely what they expect: this vehicle, with its handcrafted 4.0-liter twin-turbo V8, is built to move with authority, not necessarily to sip fuel. It serves busy executives, affluent families, or entrepreneurs who appreciate the finer things in life and require a vehicle that can effortlessly transition from school runs to interstate blasts, all while coddling its occupants and leaving nothing to be desired in terms of performance.

City and highway performance

The 2026 AMG GLS63 registers 15 MPG in city driving and 20 MPG on the highway. That 15 MPG in urban environments is entirely predictable given the vehicle’s heft, the frequent stop-and-go nature of city traffic, and the prodigious power always on tap. The GLS63’s 4.0-liter V8, paired with its intelligent 4MATIC+ all-wheel-drive system and the smooth 9-speed automatic transmission, is engineered for instantaneous response and relentless acceleration. During repeated short bursts of power, common in urban settings, fuel consumption naturally rises. However, for highway cruising, 20 MPG reflects the efficiency engineering at play. The 9-speed transmission allows the engine to settle into lower RPMs at speed, while cylinder deactivation technology, a standard feature on this powertrain, can briefly transform the V8 into a more efficient four-cylinder under light loads, further contributing to that respectable highway figure. This vehicle is built to cover vast distances with unwavering stability and effortless overtaking capability, and the 20 MPG highway rating confirms its capability for comfortable, long-distance touring.

Annual fuel cost

The EPA estimates an annual fuel cost of $3,400 for the 2026 Mercedes-Benz AMG GLS63 4matic Plus. This figure is derived from an assumption of 15,000 miles driven per year, split between city and highway driving, and based on national average fuel prices for premium gasoline. It’s a useful benchmark for potential owners to understand the operational expenses beyond the hefty purchase price. While $3,400 per year for fuel might seem substantial to some, it aligns perfectly with the expectations of the AMG GLS63 buyer. This individual is accustomed to the costs associated with owning and maintaining a high-performance luxury vehicle. The annual fuel expenditure is simply a component of the overall premium experience, a small price to pay for the unrestricted access to exhilarating power and uncompromised luxury that the AMG GLS63 delivers every single day.

Real-world expectations

In real-world driving scenarios, owners of the 2026 AMG GLS63 should largely expect their fuel economy to hover around the EPA’s combined 17 MPG, with typical variations based on driving style and conditions. If you frequently exploit the immense power of the 4.0-liter V8, engaging Sport+ mode and enjoying the ferocious acceleration, your observed MPG will, predictably, dip below the official figures. Conversely, if your commute primarily consists of open highway stretches with a light foot on the accelerator, you might occasionally exceed the 20 MPG highway rating. The AMG GLS63’s character encourages spirited driving, and it’s a car designed to be enjoyed. The integrated EQ Boost mild-hybrid system, while primarily supporting performance with an additional 21 hp and 184 lb-ft of torque, also contributes subtly to efficiency by assisting during acceleration and allowing for smooth start/stop functionality, limiting unnecessary idling. However, this is fundamentally a powerful V8 SUV, and its real-world fuel economy will always reflect that underlying mission.

How it compares

When placed alongside its direct competitors, the 2026 AMG GLS63’s 17 MPG combined rating is right where it should be. Take the BMW Alpina XB7, for instance, another three-row performance luxury SUV, which typically achieves around 17-18 MPG combined. The Aston Martin DBX707, a more performance-focused but less spacious offering, hovers in the 16-17 MPG range. Even the Porsche Cayenne Turbo GT, a two-row performance SUV with similar power, sees figures around 17 MPG combined. The buyer considering an AMG GLS63 isn’t cross-shopping with a Honda Pilot; they’re looking at the pinnacle of luxury SUVs that also deliver serious performance metrics. In this rarefied segment, fuel economy numbers are remarkably consistent because the engineering challenges of moving 5,700+ pounds with 603 horsepower (and an additional 21 hp from EQ Boost) are largely universal. For more data on similar vehicles, explore all Mercedes Benz fuel economy data or dive deeper into AMG MPG across all years.

Tips to maximize efficiency

While the AMG GLS63 is not inherently a fuel-sipper, specific driving habits can help optimize its consumption. Using the “Comfort” drive mode whenever possible will temper throttle response and engage earlier, smoother gear changes, preventing the engine from revving unnecessarily high and maximizing the benefit of the mild-hybrid system.

Maintaining a consistent speed on the highway is crucial. Engaging adaptive cruise control, if equipped, can effectively manage speeds and distances, avoiding sudden acceleration and deceleration that consume more fuel, allowing the 9-speed transmission to maintain the most efficient engine RPMs.

Regular maintenance, including proper tire inflation to the manufacturer’s recommended pressures, is key. Underinflated tires increase rolling resistance, forcing the engine to work harder and consume more fuel, regardless of the vehicle’s performance pedigree.

Adopting a smooth, progressive driving style, anticipating traffic flow, and avoiding aggressive braking and acceleration will make a noticeable difference. The power is always there when you need it, but exercising restraint during routine driving minimizes fuel consumption and enhances passenger comfort.

Considering the type of fuel used is also important. The AMG GLS63’s high-performance twin-turbo V8 is designed to run exclusively on premium unleaded gasoline. Using lower-octane fuel can not only diminish performance but also potentially reduce efficiency as the engine’s management system adjusts timing to prevent pre-ignition.