15 MPG combined. Accept it, or move along. The 2018 Mercedes-Benz AMG GLS63 isn’t for the faint of heart, nor is it built for those who prioritize efficiency above all else. This is a seven-seat sledgehammer, a luxurious land yacht with a hand-built AMG engine designed to deliver a symphony of sound and effortless acceleration. Its buyers are not cross-shopping with Priuses; they want presence, performance, and practicality, and they’re willing to pay at the pump for the privilege.

City and highway performance

The EPA estimates 13 MPG in the city and 18 MPG on the highway. Let’s be honest: the city figure is more aspirational than realistic for many owners. Stop-and-go traffic coupled with the temptation to unleash the AMG’s power will likely drag that number down. The highway figure is more achievable, particularly on longer road trips. However, even on the open road, maintaining a steady 75-80 mph will require a fair amount of throttle, impacting efficiency. Ultimately, driving style and conditions play a significant role, but expect to hover around these official figures.

Annual fuel cost

The EPA estimates an annual fuel cost of $3,850 for the 2018 Mercedes-Benz AMG GLS63. This figure is based on driving 15,000 miles per year, with 55% of those miles driven in the city and 45% on the highway. It also assumes a national average fuel price, which can fluctuate significantly depending on location and grade of fuel. Considering the GLS63 requires premium fuel, owners in areas with higher gas prices can expect to exceed this estimate. This $3,850 figure is a stark reminder that performance comes at a price.

Real-world expectations

While the EPA provides a standardized benchmark, real-world fuel economy often deviates. GLS63 owners frequently find themselves below the advertised figures, especially those who enjoy the car’s performance capabilities. Short trips, frequent acceleration, and idling in traffic quickly diminish fuel efficiency. Conversely, drivers who prioritize smooth acceleration and anticipate traffic flow can potentially achieve numbers closer to the EPA estimates. Ultimately, responsible driving habits can influence fuel consumption, but expecting Prius-like numbers is a fool’s errand.

How it compares

Compared to other performance SUVs, the AMG GLS63’s fuel consumption is predictably thirsty. The BMW X5 M, with its 4.4L twin-turbo V8, delivers similar fuel economy numbers, hovering around 14 MPG combined. The Range Rover Sport SVR, another powerful option, also resides in this fuel-guzzling territory. Even the less potent Volvo XC90 T8 plug-in hybrid, while offering a theoretical electric range, only achieves around 27 MPG combined when operating as a standard hybrid, a number still far above the AMG GLS63. For those seeking better MPG, a downsize to a non-AMG GLS model may be necessary, although sacrificing a significant amount of performance. For comparison, you can find all Mercedes Benz fuel economy data on our site. Explore AMG MPG across all years as well.

Tips to maximize efficiency

Minimize aggressive acceleration. The AMG GLS63’s engine is responsive, making it tempting to unleash its power frequently. However, each burst of acceleration drains fuel. Smooth, gradual acceleration will significantly improve fuel economy, especially in city driving.

Use cruise control on the highway. Maintaining a consistent speed minimizes unnecessary acceleration and deceleration, optimizing fuel consumption. Engage cruise control on long stretches of highway to maintain a steady pace and improve efficiency.

Ensure proper tire inflation. Underinflated tires increase rolling resistance, forcing the engine to work harder and consume more fuel. Regularly check and maintain the recommended tire pressure to optimize fuel economy. The correct tire pressure is usually listed on a sticker inside the driver’s side doorjamb.

Reduce idling time. Idling consumes fuel without covering any distance. If you anticipate being stationary for more than a minute, turn off the engine. Modern vehicles can restart quickly and efficiently, minimizing the impact of restarting on fuel consumption.