The 2023 Mercedes-Benz GLS450 4matic’s 20 MPG combined fuel rating isn’t the primary reason people buy it. This vehicle is designed to smoothly transport up to seven adults in quiet comfort, so its fuel economy should be understood as the cost for that experience. Buyers are usually affluent suburbanites who value space, safety, and prestige more than saving money on gas. They accept that the GLS450 uses more fuel because it offers a driving experience few other SUVs can deliver.

City and highway performance

The GLS450’s EPA ratings show where it compromises in the city. The 18 MPG city rating reflects hauling a vehicle weighing over 5,000 pounds while constantly stopping and starting. However, on the highway, it gets an EPA-estimated 23 MPG. The GLS450 excels here, easily maintaining speed, allowing its nine-speed automatic transmission to use less fuel. Long trips are more comfortable, and the vehicle drives quietly, even if the city MPG brings range anxiety.

Annual fuel cost

The EPA estimates the annual fuel cost for the 2023 Mercedes-Benz GLS450 4matic at $2,900. This is based on driving 15,000 miles per year and assumes a national average fuel price. While this gives a comparison point, your actual fuel expenses depend on your driving, local fuel prices, and how much you drive in the city versus on the highway. Rapid acceleration, premium fuel, or high gas taxes can increase the annual cost.

Real-world expectations

While the EPA provides a standard, real-world GLS450 MPG varies. Driving fast, short trips, and heavy loads reduce fuel economy. Driving gently, driving at consistent highway speeds, and maintaining the car helps you get close to the EPA estimates, or possibly beat them. Understanding how you drive and how you use the GLS450 affects how much fuel it uses is key. Watch your trip computer and track fuel purchases to understand your fuel costs.

How it compares

The GLS450’s fuel economy is in the middle for three-row luxury SUVs. The BMW X7 xDrive40i, which has a similar engine, gets similar fuel economy. The Volvo XC90 Recharge plug-in hybrid gets better fuel economy when its hybrid system is operating, but it must be charged regularly. The Land Rover Range Rover, especially with its larger engines, typically gets lower MPG. All Mercedes Benz fuel economy data shows that larger SUVs tend to use more gas. For buyers considering the GLS450 MPG across all years, comparing it against its rivals is important to determine if it fits their needs.

Tips to maximize efficiency

Use the GLS450’s driving modes. Choosing “Comfort” or “Eco” mode softens the accelerator and optimizes the transmission to save fuel. Avoid accelerating and braking hard, as this wastes fuel. Gentle inputs are key to maximizing MPG.

Keep your tires inflated. Underinflated tires increase rolling resistance, which increases fuel consumption. Check your tire pressures often and inflate them to the recommended levels found on the doorjamb sticker. This simple action can greatly improve your gas mileage.

Reduce aerodynamic drag. Remove roof racks or cargo carriers when you are not using them. These items disrupt airflow and increase wind resistance, which reduces fuel economy, especially at highway speeds. Streamlining the GLS450’s shape helps it move through the air more efficiently.

Maintain your car. A well-maintained engine uses less fuel. Follow the manufacturer’s service intervals for oil changes, air filter replacements, and spark plug inspections. Addressing small problems early can prevent them from becoming larger problems that reduce fuel economy.

Reduce weight. Remove unnecessary items from the vehicle. Extra weight makes the engine work harder, which burns more fuel. Regularly clean out the trunk and cargo area to reduce excess baggage impacting your MPG.