Mercedes GL-Class 2015: Legendary Highway Mileage
The 2015 Mercedes-Benz GL-Class offers remarkable highway mileage for a full-size luxury SUV, thanks to its powerful yet efficient powertrains and advanced engineering. This guide will help you understand and maximize its legendary fuel economy on your next road trip.
The open road calls, and for many luxury SUV owners, the question of fuel efficiency on those long journeys is always on their mind. If you’re the proud owner of a 2015 Mercedes-Benz GL-Class, or perhaps considering one, you’re likely wondering about its highway mileage. This premium, spacious SUV is beloved for its comfort and capability, but does it deliver on the promise of efficient cruising? Many owners find that achieving good gas mileage in such a robust vehicle can be a bit of a puzzle. Don’t worry, we’re here to break down exactly what you can expect from your 2015 GL-Class on the highway and how to get the most out of every gallon, no matter which engine you have.
Understanding the 2015 Mercedes-Benz GL-Class Engine Options and Their Mileage
The 2015 Mercedes-Benz GL-Class was offered with a few distinct engine choices, each tuned for a balance of power and efficiency. Understanding which engine powers your GL is the first step to knowing its highway mileage potential. The most common configurations are the GL 350 BlueTEC (diesel) and the GL 450 (gasoline). For those seeking more power, the GL 550 was also available.
GL 350 BlueTEC: The Diesel Champion
The GL 350 BlueTEC is powered by a 3.0-liter V6 turbodiesel engine. This powerplant is renowned for its excellent torque and, critically, its impressive fuel economy, especially on the highway. Diesel engines, in general, tend to be more fuel-efficient than their gasoline counterparts, particularly at constant speeds, making them ideal for long-distance driving.
Engine: 3.0L V6 Turbodiesel
Horsepower: 240 hp
Torque: 455 lb-ft
EPA Estimated Highway MPG: Around 26 MPG (this can vary slightly based on driving conditions and specific vehicle options)
The BlueTEC system also incorporates AdBlue (Diesel Exhaust Fluid) injection to reduce emissions, a technology that was quite advanced for its time and contributes to cleaner, more efficient operation.
GL 450: The Balanced Gasoline Option
The GL 450 features a 4.7-liter V8 biturbo gasoline engine. While it offers more horsepower and a smoother, quieter experience compared to some diesel engines, its highway mileage is typically a bit less than the GL 350 BlueTEC. However, it still provides commendable fuel efficiency for a vehicle of its size and class. Mercedes-Benz engineers put significant effort into optimizing these V8s for better fuel consumption through technologies like direct injection and start/stop systems.
Engine: 4.7L V8 Biturbo Gasoline
Horsepower: 362 hp
Torque: 406 lb-ft
EPA Estimated Highway MPG: Around 20 MPG (again, subject to variations)
This engine is a great choice if you prioritize a more potent acceleration and refined engine note over maximum fuel savings.
GL 550: The Performance Enthusiast’s Pick
For those who crave maximum power and performance, the GL 550 comes with a more potent version of the 4.7-liter V8 biturbo engine. This version boasts higher horsepower and torque figures, designed for exhilarating acceleration and towing capability. As expected, this increased performance comes at the cost of fuel efficiency on the highway.
Engine: 4.7L V8 Biturbo Gasoline (higher output)
Horsepower: 449 hp
Torque: 516 lb-ft
EPA Estimated Highway MPG: Around 17 MPG
While its highway mileage is the lowest of the trio, it still represents a respectable figure for a vehicle packing such a powerful punch.
Key Factors Influencing Your 2015 GL-Class Highway Mileage
Beyond the engine under the hood, numerous factors significantly impact how much fuel your 2015 GL-Class consumes on the highway. Understanding these variables can empower you to make adjustments that lead to better mileage.
Driving Habits: The Biggest Contributor
How you drive has a profound effect on fuel economy. Aggressive acceleration and hard braking are the enemies of good mileage, especially in a large SUV.
Smooth Acceleration: Gradually increase your speed rather than flooring the accelerator. This allows the engine to reach cruising speed more efficiently.
Anticipatory Driving: Look ahead and anticipate traffic conditions. Letting off the accelerator early to coast to a stop or slow down is far more efficient than braking hard at the last moment.
Consistent Speed: Maintaining a steady speed on the highway is crucial. Cruise control can be a valuable tool for this, as it helps prevent unnecessary fluctuations in speed. However, on very hilly terrain, sometimes disengaging cruise control and manually managing speed can be more efficient.
Tire Pressure: A Simple Yet Effective Factor
Properly inflated tires are essential for optimal fuel economy. Underinflated tires increase rolling resistance, forcing the engine to work harder to maintain speed.
Check Regularly: It’s recommended to check your tire pressure at least once a month, and before any long road trips.
Recommended PSI: Always refer to the sticker located on the driver’s side doorjamb for the manufacturer’s recommended tire pressure for your specific GL-Class. Never exceed the maximum pressure listed on the tire sidewall.
Temperature Effects: Tire pressure can decrease in colder weather and increase in warmer weather. Adjust accordingly.
Learn more about the importance of proper tire inflation from the National Highway Traffic Safety Administration (NHTSA): https://www.nhtsa.gov/campaign/tire-safety
Vehicle Load: Less Weight, Better Mileage
The heavier your vehicle, the more fuel it will consume. Transporting unnecessary weight can significantly decrease your highway mileage.
Pack Smart: Only bring what you truly need for your journey. Remove any unnecessary heavy items from the cargo area or cabin before departing.
Roof Racks and Cargo Carriers: If you use roof racks or cargo boxes, be aware that they increase aerodynamic drag, further impacting fuel economy. The added weight also contributes. Remove them when not in use.
Aerodynamics: Minimizing Drag
As a large SUV, the GL-Class has a considerable frontal area, meaning it’s susceptible to aerodynamic drag, especially at higher speeds.
Close Windows: At highway speeds, keeping your windows closed and using the climate control system is generally more fuel-efficient than driving with windows open.
Avoid Unnecessary Exterior Attachments: Anything that protrudes from the vehicle’s profile can create drag.
Maintenance: Keeping Your GL in Top Shape
Regular maintenance ensures all components are functioning optimally, which directly translates to better fuel efficiency.
Engine Tune-Up: Ensure your engine is properly tuned. This includes clean air filters, spark plugs (if applicable to your engine type), and ensuring the fuel injection system is working correctly.
Oil Changes: Using the correct grade of synthetic oil recommended by Mercedes-Benz can reduce engine friction and improve efficiency.
Exhaust System: A properly functioning exhaust system is key to engine performance and efficiency. Any leaks or blockages can negatively impact mileage.
For detailed maintenance schedules and recommendations specific to your 2015 GL-Class, consult your owner’s manual or a certified Mercedes-Benz service center.
Maximizing Your 2015 GL-Class Highway Mileage: Practical Tips and Techniques
Now that we understand the factors at play, let’s delve into actionable strategies to maximize your 2015 GL-Class’s highway mileage.
Utilize Cruise Control Effectively
As mentioned earlier, cruise control is a fantastic tool for maintaining a steady speed on flat, open highways. It prevents your right foot from making subtle, efficiency-robbing adjustments.
When to Use: Ideal for long stretches of highway with consistent traffic flow.
When to Avoid: On very hilly or mountainous terrain, or in heavy, stop-and-go traffic, manual control might be more fuel-efficient.
Optimize Speed for Efficiency
There’s a sweet spot for highway fuel economy. Driving significantly faster than the speed limit will drastically reduce your MPG.
The “Sweet Spot”: For most vehicles, including the 2015 GL-Class, the most fuel-efficient cruising speed is typically between 55-65 mph. Every 5 mph over 50 mph can reduce fuel economy by as much as 7%.
Balance Speed and Time: While slower speeds save fuel, consider your overall travel time. A slight increase in speed might be worth the time saved on longer journeys, but avoid excessive speed.
Plan Your Route and Stops
Careful planning can minimize backtracking and reduce time spent idling.
Idling Wastes Fuel: Every minute your engine is running while stationary consumes fuel without covering any distance. If you anticipate a stop longer than a minute, consider turning off the engine.
Fuel Availability: Plan your fuel stops to coincide with breaks. Many modern Mercedes-Benz vehicles have sophisticated navigation systems that can help locate fuel stations along your route.
Leverage Eco Mode (If Equipped)
Some models or trim levels of the 2015 GL-Class might have an “Eco” mode in their drive settings. This mode often adjusts throttle response and transmission shift points to prioritize fuel economy.
How it Works: Typically sharpens throttle response slightly and delays upshifts to keep engine RPMs lower.
Test It Out: Experiment with Eco mode on a familiar highway route and compare your results to your usual driving mode.
Keep Up with General Maintenance
A well-maintained vehicle is an efficient vehicle. Beyond what’s listed earlier, consider these general maintenance points:
Cleanliness: A clean car, especially a clean undercarriage, can reduce aerodynamic drag slightly.
Wheel Alignment: Proper wheel alignment ensures your tires aren’t dragging or fighting each other, which saves fuel.
Comparing Highway Mileage: Key Models
To provide a clearer picture, let’s look at the estimated highway mileage figures for the primary 2015 GL-Class models side-by-side. These are EPA estimates and real-world results may vary.
| Model | Engine | Horsepower | Torque | Est. Highway MPG |
| :—————– | :—————————– | :——— | :——— | :————— |
| GL 350 BlueTEC | 3.0L V6 Turbodiesel | 240 hp | 455 lb-ft | ~26 MPG |
| GL 450 | 4.7L V8 Biturbo Gasoline | 362 hp | 406 lb-ft | ~20 MPG |
| GL 550 | 4.7L V8 Biturbo Gasoline (HP) | 449 hp | 516 lb-ft | ~17 MPG |
Note: Mileage figures are approximate and can vary based on driving conditions, maintenance, tire pressure, and load. Always refer to your vehicle’s specific window sticker or owner’s manual for official ratings.
As you can see, the GL 350 BlueTEC stands out as the most fuel-efficient option for highway cruising among the 2015 GL-Class models, a testament to the efficiency of modern diesel technology.
Can You Improve Your 2015 GL-Class’s Existing Highway Mileage?
While the inherent design of the vehicle sets a baseline, there’s always room for improvement through diligent driving and maintenance.
Regular Servicing is Key
Fuel System Cleaning: Occasionally using a quality fuel system cleaner can help maintain optimal injector performance, leading to more efficient fuel combustion.
Air Filter Replacement: A clogged air filter restricts airflow to the engine, making it work harder. Replacing it according to the maintenance schedule is crucial. You can find reputable air filters from brands like Mann-Filter or Mahle.
Spark Plugs (GL 450/550): For the gasoline models, ensuring spark plugs are in good condition and replaced at recommended intervals is vital for efficient combustion.
Consider Low Rolling Resistance Tires
When it’s time to replace your tires, opting for tires specifically designed for low rolling resistance can offer a modest improvement in fuel economy. While Mercedes-Benz outfits these vehicles with premium tires, exploring options from manufacturers like Michelin (e.g., their Energy Saver line) or Continental might yield slight benefits. Always ensure they meet the load and speed ratings required for your GL-Class.
Driving Style Adjustments
The most impactful changes often come from adjusting your driving habits:
Moderation is Key: Avoid rapid acceleration and deceleration. Smooth inputs are crucial.
Coasting: Anticipate slowdowns and traffic lights, and use gravity and momentum by coasting whenever possible.
Reduce Idling: Turn off the engine if you anticipate being stopped for more than a minute.
Understanding Weight Distribution
While you won’t remove weight from your engine or drivetrain, mindful packing can make a difference.
Even Load: Distribute weight in the cargo area evenly to maintain the vehicle’s balance.
* Avoid Overloading: While modern SUVs are built to handle significant loads, exceeding the maximum payload capacity will negatively impact fuel economy and vehicle dynamics. Consult your owner’s manual for payload specifications.
Frequently Asked Questions (FAQs)
What is the typical highway MPG for a 2015 Mercedes-Benz GL 350 BlueTEC?
The 2015 Mercedes-Benz GL 350 BlueTEC, with its 3.0-liter V6 turbodiesel engine, typically achieves around 26 miles per gallon (MPG) on the highway. This makes it the most fuel-efficient option in the GL-Class lineup for long-distance driving.
How does the GL 450’s highway mileage compare to the GL 350 BlueTEC?
The 2015 GL 450, powered by a 4.7-liter V8 biturbo gasoline engine, generally offers a highway MPG of about 20 MPG. This is lower than the GL 350 BlueTEC, reflecting the inherent efficiency differences between gasoline and diesel engines in this class.
What factors most significantly impact my 2015 GL-Class highway mileage?
The most significant factors impacting your highway mileage are your driving habits (acceleration, braking, speed), tire pressure, the weight of the vehicle and its load, and the overall aerodynamic efficiency. Regular vehicle maintenance also plays a crucial role.
Is it true that driving faster decreases fuel economy significantly?
Yes, absolutely. For vehicles like the 2015 GL-Class, driving at speeds above 60-65 mph can lead to a noticeable decrease in fuel economy. Every 5 mph increase above 50 mph can reduce your MPG by as much as 7% due to increased aerodynamic drag.
How can I improve my existing highway mileage on my 2015 GL-Class?
You can improve your highway mileage by driving smoothly, maintaining correct tire pressure, reducing unnecessary vehicle weight, using cruise control on flat terrain, and ensuring regular maintenance, including clean air filters and properly functioning engine components.
Will towing affect my 2015 GL-Class highway mileage?
Yes, towing will significantly reduce your highway mileage. The added weight and aerodynamic drag from a trailer place a much greater burden on the engine and drivetrain, leading to lower MPG figures. The exact reduction depends on the size and weight of the trailer.
Can using the air conditioning impact my highway mileage?
Yes, using the air conditioning system will consume engine power and thus reduce fuel economy, though the impact is generally less significant at steady highway speeds than it is in stop-and-go city driving. Keeping windows closed at highway speeds and using the climate control is usually more efficient than open windows.
Conclusion
The 2015 Mercedes-Benz GL-Class, particularly the GL 350 BlueTEC variant, has earned its reputation for being a capable and surprisingly fuel-efficient luxury SUV on the highway. By understanding the engine powering your vehicle and embracing mindful driving techniques, meticulous maintenance, and sensible habits, you can truly unlock its legendary highway mileage potential. Whether you’re embarking on a cross-country adventure or simply enjoying a scenic drive, knowing how to maximize your MPG ensures a more economical and enjoyable journey in your sophisticated Mercedes-Benz. Enjoy the ride, and happy trails!
