The 2017 Mercedes-Benz GLS450 4matic gets 19 MPG combined. It’s not the most fuel-efficient SUV, but it’s a figure that most buyers in this segment accept. This vehicle is built for hauling families and cargo in comfort and with all-weather capability, and those factors are usually more important than saving gas. Buyers are willing to trade some fuel economy for the smooth power of the 3.0L turbocharged V6 and the 4matic all-wheel-drive system.

City and highway performance

The EPA estimates the GLS450 4matic gets 17 MPG in the city and 22 MPG on the highway. The city figure reflects the stop-and-go driving common for larger vehicles, where frequent acceleration and braking reduce mileage. The highway number, while not great, is a more reasonable result of the efficient (for its time) 9-speed automatic transmission and the engine’s ability to cruise at higher speeds. Remember that these figures are based on standardized testing; your actual mileage will change depending on driving style, load, and terrain.

Annual fuel cost

The EPA estimates the yearly fuel cost for the 2017 Mercedes-Benz GLS450 4matic at $3,050. This is based on driving 15,000 miles per year and using national average fuel prices. This number will vary depending on where you live (fuel prices fluctuate regionally), how much you drive, and how heavy your foot is on the accelerator. However, it provides a useful comparison of the GLS450 to other vehicles in its class. The EPA’s calculation assumes a mix of city and highway driving that reflects typical driving habits.

Real-world expectations

While the EPA numbers are a guide, real-world driving is often different. GLS450 owners often report numbers close to the EPA estimates, but aggressive driving, towing, or frequent short trips can significantly reduce fuel economy. Sticking to highway driving at moderate speeds can sometimes yield slightly better results than the EPA highway estimate. By watching your driving habits and fuel consumption, you can get a more accurate picture of your GLS450’s efficiency in your specific driving conditions. You can also explore GLS450 MPG across all years.

How it compares

Among luxury three-row SUVs, the 2017 GLS450’s fuel economy is about average. The BMW X5 xDrive35i (with its 3.0L inline-6) had similar fuel economy figures, around 17 MPG city and 24 MPG highway. The Volvo XC90 T6, with its supercharged and turbocharged 2.0L four-cylinder, aimed for better efficiency, achieving around 20 MPG city and 27 MPG highway. Audi’s Q7, with a supercharged 3.0L V6, posted figures comparable to the BMW. The comparison is important because buyers in this segment prioritize luxury and space, and are increasingly conscious of lower fuel costs, especially given the GLS450’s thirst compared to some of its rivals offering four cylinder or hybrid options. Explore all Mercedes Benz fuel economy data to see how the GLS450 compares against other models from the manufacturer.

Tips to maximize efficiency

The GLS450’s smooth-shifting 9-speed automatic transmission keeps the engine in its most efficient range. Avoid aggressive acceleration and hard braking to allow the transmission to do its job. Gentle, gradual acceleration saves fuel and helps give a smoother, more comfortable ride for your passengers.

Make sure your tires are properly inflated. Underinflated tires increase rolling resistance, which makes the engine work harder and use more fuel. Check your tire pressure regularly, ideally before each drive, and inflate them to the recommended pressure listed on the sticker inside your driver’s side door.

Reduce unnecessary weight. Carrying extra cargo in the GLS450 adds weight, impacting fuel economy. Remove items from the trunk or rear seats that you don’t need to carry regularly. Every extra pound lowers efficiency.

Consider using the “Comfort” or “Eco” driving modes, if equipped. These modes adjust the engine and transmission settings to prioritize fuel efficiency over performance. While they may reduce responsiveness slightly, they can affect fuel consumption, especially during city driving.