15 MPG combined is not going to win any awards, especially with so many hybrid SUVs available. But the 2019 Mercedes-Benz AMG GLS63 isn’t about awards or hypermiling. It’s about brutal power, a commanding presence, and the ability to haul seven passengers in ridiculous comfort while leaving nearly everything else on the road in your wake. This is a vehicle for a very specific type of buyer: the deep-pocketed parent who needs the space of a full-size SUV but refuses to sacrifice performance. They understand the trade-off, exhilarating acceleration and a sonorous exhaust note versus frequent trips to the gas station and they’re perfectly fine with it.

City and highway performance

The EPA estimates for the AMG GLS63 break down to 13 MPG in the city and 18 MPG on the highway. Know that those numbers are achieved under ideal conditions, which aren’t often replicated in the real world. The city figure reflects stop-and-go traffic where the heavy GLS63 is constantly accelerating and decelerating its substantial weight. The highway figure is more achievable, but it assumes a steady speed and minimal hard acceleration. The reality is that this vehicle begs to be driven aggressively, and that powerful 5.5L V8 will happily oblige, decimating those EPA estimates every time you mash the throttle.

Annual fuel cost

The EPA calculates the annual fuel cost for the 2019 Mercedes-Benz AMG GLS63 at $3,850. 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. The calculation also uses the national average fuel price at the time of the EPA’s testing. It’s safe to assume that number could easily be higher if fuel prices continue to rise, if you do more city driving than average, or if you have a particularly heavy right foot. However, if you’re considering an AMG GLS63, chances are the annual fuel cost is a secondary concern. You can find all Mercedes Benz fuel economy data on our site.

Real-world expectations

Seeing numbers close to the EPA’s 18 MPG on the highway might be possible during long, steady road trips, but consistently achieving the 13 MPG city figure is less likely. The AMG GLS63 is a heavy vehicle, and its performance-oriented engine and drivetrain are not designed for maximizing fuel efficiency. Expect to see numbers closer to 11-12 MPG in typical city driving conditions.

Many owners report averaging around 14 MPG in mixed driving, which aligns with the vehicle’s inherent performance characteristics. The AMG MPG across all years also shows a trend of lower fuel economy in larger vehicles.

How it compares

The AMG GLS63 isn’t exactly in a class of its own, but its combination of size, performance, and luxury makes for a narrow field. The BMW X7 M50i, with its 4.4L V8, achieves a slightly better 18 MPG combined. The Cadillac Escalade, though not a direct performance rival, manages a similar 17 MPG combined with its 6.2L V8. The Range Rover Sport SVR, packing a supercharged 5.0L V8, lands at a dismal 15 MPG combined, matching the AMG GLS63. This solidifies the expectation that immense power necessitates a trade-off at the pump. These comparisons highlight the simple fact that if you want a large, luxurious SUV with serious power, you’re going to pay for it, both at the dealership and at the gas station.

Tips to maximize efficiency

The AMG GLS63 isn’t designed for fuel sipping, but there are some strategies you can employ to reduce your consumption. Avoid aggressive acceleration and hard braking whenever possible. The 5.5L twin-turbo V8 delivers enormous torque, which means you don’t need to floor the throttle to get up to speed. Smooth, gradual acceleration will significantly improve your fuel economy.

Use the car’s driving modes. The “Comfort” mode detunes the engine and optimizes the transmission for efficiency, which can help you conserve fuel in less demanding situations. Don’t expect miracles. This mode is mostly designed for comfort and won’t drastically improve your MPG.

Keep your tires properly inflated. Underinflated tires increase rolling resistance, which forces the engine to work harder and consumes more fuel. Check your tire pressures regularly and maintain the recommended inflation level, which is listed on a sticker inside the driver’s side doorjamb.

Minimize idling. Idling wastes fuel, so avoid letting the engine run unnecessarily. If you’re stopped for more than a minute, it’s generally more efficient to turn off the engine and restart it when you’re ready to go. Modern vehicles are designed to handle frequent start-stop cycles without causing excessive wear and tear.

Consider planning your routes to avoid heavy traffic. Stop-and-go traffic is a major fuel economy killer, especially in a large SUV like the AMG GLS63. If possible, choose routes with less congestion, even if it means a slightly longer distance. The steady highway cruising speed will reward you with improved MPG.