14 MPG combined is far from stellar, but it’s the price of admission for drivers who demand the ultimate in three-row SUV performance. The 2017 Mercedes-Benz AMG GLS63 isn’t bought for its frugality; it’s purchased by those who want a hand-built AMG engine, imposing road presence, and the ability to rocket from 0 to 60 mph in a scant 4.5 seconds while coddling up to seven occupants in leather-lined luxury. Fuel economy is a tertiary concern, at best.

City and highway performance

The EPA estimates for the AMG GLS63 break down to 13 MPG in the city and 17 MPG on the highway. The city figure reflects the demands placed on the powerful 5.5L V8 while navigating stop-and-go traffic, with frequent bursts of acceleration quickly diminishing fuel reserves. The highway figure, while still modest, shows the engine’s ability to cruise at a relatively relaxed pace, aided by the seven-speed automatic transmission. However, even on the open road, the sheer weight and aerodynamic profile of the GLS63 prevent it from achieving truly respectable economy.

Annual fuel cost

The EPA calculates the annual fuel cost for the 2017 Mercedes-Benz AMG GLS63 at $4,150. This figure is based on driving 15,000 miles per year, with a mix of city and highway driving, and using the national average fuel price at the time of calculation. Obviously, this cost can vary significantly depending on individual driving habits and local fuel prices. Drivers with a heavier foot, or those who primarily drive in congested urban areas, can expect to spend even more.

Real-world expectations

While the EPA figures provide a benchmark, real-world fuel economy often differs, especially with a vehicle like the AMG GLS63. The highly responsive throttle and addictive exhaust note encourage drivers to tap into the engine’s considerable power reserves regularly, negatively impacting fuel consumption. Aggressive acceleration, frequent gear changes, and the urge to exploit its prodigious torque will likely push figures below the EPA estimates. Conversely, a driver with a more disciplined approach and consistent highway driving might see numbers closer to, or even slightly above, the 17 MPG highway figure.

How it compares

The AMG GLS63 exists in a niche of high-performance, large SUVs. The BMW X5 M, with its 4.4L twin-turbo V8, manages a slightly better 16 MPG combined. The Land Rover Range Rover Sport SVR, while equally thirsty in practice, is rated at 15 MPG combined. While these differences might seem small, they can add up over time. Considering all Mercedes Benz fuel economy data, the AMG GLS63 is clearly positioned at the bottom when considering MPG. Buyers considering AMG MPG across all years know that performance comes before efficiency.

Tips to maximize efficiency

Minimize aggressive acceleration. The AMG GLS63’s immense power is tempting to unleash, but doing so frequently will dramatically reduce fuel economy. Adopt a smoother driving style, anticipating traffic flow and avoiding unnecessary hard starts.

Use cruise control on the highway. Maintaining a consistent speed on long drives will help the engine operate more efficiently. Avoid excessive speeding, as aerodynamic drag increases exponentially at higher velocities.

Regularly check tire pressure. Underinflated tires increase rolling resistance, which in turn increases fuel consumption. Ensure your tires are inflated to the recommended pressure, which can be found on a sticker inside the driver’s side doorjamb.

Consider using a fuel additive designed to clean fuel injectors. A clean fuel system ensures optimal combustion, maximizing power and efficiency. However, check your owner’s manual to confirm compatibility with your vehicle’s fuel system.

Reduce unnecessary weight. Carrying excessive cargo adds to the vehicle’s overall weight, requiring more energy to accelerate. Remove anything you don’t need from the trunk and passenger compartment.