Towing dual axle trailers with our Mercedes GL SUV:
Shortly after purchasing our used 2007 GL450 4Matic with the usual Air Suspension and the not-so-common Class IV factory tow package, I purchased a 2,000 lb Tandem Axle Trailer to tow our 5,000 lb Kubota 4WD Loader/Backhoe between our Pleasant Mount PA and Kingston NY properties.
The GL can pull 7,500 lbs but has a lower than normal 600 lb tongue weight limit (8%, instead of the common 10%).I added a Tekonsha Prodigy 90195 Brake Controller to the factory installed wiring under the dashboard to power the Electric Trailer Brakes.
The trailer brake lights would fail with a Brake Light Failure message immediately upon stepping on the brakes. The "4-ways" hazard and turn signal lights would work as normal, but no brake lights on the trailer. (The hitch receiver looked like it had the original paint, so the previous owner probably never towed a trailer in the 8+ years they owned it.) Jason at Keeler Motors in Latham NY quickly determined that the Rear SAM original programing was for the non-USA variant, but a quick reprogramming fixed the Brake Light error. (Thank you Jason!)
Many would say we'd need the diesel motor or at least the 550 motor to pull the full 7500 lb capacity, but short of normal automatic downshifts and a minor slow down as we tow up good size hills, the GL450 does a fine job of Towing our equipment. In April 2021, we drove to Houston TX to purchase a 2015 Lance 1685 "4 Season" 5400 lb GVWR travel trailer. Like our tandem 'lowboy' trailer, the RV trailer had only the 2-5/16" ball hitch and no Sway control or any Weight Distribution System. However, the increased cross-section of the 20' camper made going faster than 63 mph unnerving, so we charted the 'scenic routes' back home as we visited a few campgrounds and other pleasant sightseeing stops on our return. (Gulpha Gorge Campground at Hot Springs National Park AR with my Senior Lifetime National Park pass was a favorite!)
We had 'settled for' the smaller 20' model with its 275 lb tongue/'Hitch' weight as we learned from the Lance RV forum that many would have more than double the dry Hitch weight. But being more familiar now with the layout, we decided to get the 22' trailer rated at 335 lb tongue weight & 5700 lb GVWR, and just be very careful to not load up the front and exceed the 600 lb limit, as is often done by most. I could relocate the camper's front mounted battery and spare tire if needed. We soon drove to NH to purchase a 2015 Lance 1985 trailer and it came with a Husky Center Line TS Weight Distributing Hitch which definitely helped with sway control.
The Husky sliding torsion bar system was noisier than I cared for, so I purchased a Blue Ox SwayPro system and sold the Husky system. The SwayPro system is silent and much easier/safer to load - a great improvement!I bought a used Sherline Trailer Tongue Weight Scale so I can easily monitor the tongue weight.
In 2023, we surpased 310,000 miles (half million kilometers)! We already had our first Quarter Million Kilometer 'High Mileage Award', but with now over 310,000 miles on it, we've received our second (500,000 km) Mercedes-Benz Classic Center medallion.
You can read much more about Towing with a Mercedes on the Forums at MBWorld.org, and more about our Luxury Towing machine at Kropf.us/2007GL450.