Roaming the World: Mercedes Unimog Based GXV Adventure Vehicle
Where Does the World's Most Capable Adventure Vehicle Come From?
After reading an article in National Geographic in the mid-1980s about a vehicle built on an old 1960s Mercedes Unimog military chassis, Mike Van Pelt was inspired. It took 20 years to realize his dream, but once he built his own Unimog-based adventure vehicle, he and his wife ended up driving it all the way to the tip of South America.
Upon arriving home, they decided to start their own company, building Unimogs for like-minded world adventurers. We saw a production GXV unit at a Southern California outdoor show and went with the couple and their vehicle for a day at a local OHV park, so we could see for ourselves what this Global Xpedition Vehicle is all about.
This GXV is based on a 2004 Mercedes Unimog U500 chassis and is powered by a Mercedes 7.2-liter turbodiesel with a 16-speed Telligent Mercedes transmission. They are four-wheel drive with front, rear, and center locking differentials. GXV will switch to the next-generation Unimog chassis in 2010 or so, and the company will unveil the specifics of the new model later this year.
The house or coach of the GXV is attached to the chassis frame with a three-point Kinetic mechanism that features two structural isolation bearings and one pivot bearing. What this means is that torque isn't transferred to the house/coach portion of the Xpedition Unit. With 20 inches of ground clearance, a set of steps is a must. In this case, a stainless aluminum stair system pulls out of a storage slot below the door and when lowered creates easy entry into the cabin. The truck also has a massive rear-storage compartment that you can reach without needing steps.
The Unimog unit has a GVWR of 26,000 or 33,000 pounds and an exterior cargo-carrying capacity of 50 to 70 cubic feet. Two fuel tanks hold a total of 110 gallons of diesel, the fuel source for everything on the coach that isn't electrical. One of the two important lessons Mike learned during the odyssey to Tierra del Fuego was that in some places of the world you cannot depend upon LPG as a fuel source for equipment (auxiliary generator, furnace, cook-top, water heater, etc). Unlike North America, the infrastructures for refueling LPG tanks in Central and South America aren't standardized, which means the LP fittings for them are unpredictable, holding an adventurer hostage when it comes to refueling. Going diesel made sense.
The second lesson learned on their trip to the southern hemisphere was that not everyone uses AC electrical systems that are compatible with 60-hertz, 120-volt systems. Many continents have 230-volt, 50-hertz AC shore power. As a result, the GXV has parallel AC electrical systems that use both. The GXV senses the type of electrical system to which it is connected and automatically switches to it (this is totally transparent to the end user).
Rooftop solar panels charge the massive sealed gel-cell battery packs and the GXV's residential electrical systems draw DC from the house batteries, which is inverted into either 120-volt, 60-cycle pure sine-wave AC or 230-volt power, as required by the user. To enhance the Xpedition Vehicle's self-reliance, it's equipped with redundant systems for power, heat, and hot water. In addition to powering the cabin through shore power (120- and 230-volt) or solar, the batteries are also charged by the truck's alternator. An ingenious choice for the GXV is the auxiliary three-cylinder industrial Isuzu diesel engine, which is the power source for two important (yet very different) functions. First, the Isuzu drives two alternators that charge the house batteries as another method of power. Second, it powers the compressor, the heart and soul of the 33,000-btu house air-conditioner, as well as the 33,000-btu heater.
A Webasto closed-loop diesel-fired boiler is the source of heat for domestic hot water and can be used to pre-heat the Mercedes turbodiesel. Interestingly, the reverse also is true. Engine heat from the coolant can be tapped into as a heat source for the interior cabin/house and for domestic hot water. The two-burner cooktop is diesel and all interior lights are DC.
Residential features include a street-side dry bath with a separate full-size standup shower, lavvy, and a cassette-style marine toilet. Two flatscreen LCD televisions are standard, along with a state-of-the-art sound system and DVD player. The (almost) queen-size bed lies side to side across the back of the cabin. The curbside galley features solid wood cabinetry, solid-surface countertops, a three-cubic-foot refrigerator, and a separate three-cubic-foot freezer drawer, both of which operate on DC. A stainless-steel sink and a convection/grill microwave round out the full-service galley. The dinette, located across the front of the coach, seats four and converts quickly into sleeping quarters for two adults. Unlike motor coaches built on a conventional-style chassis, the GXV does not include a passageway between the cab and the cabin.
At the OHV park, we watched in amazement as the GXV addressed the terrain as ATVs and motorcycles rolled alongside. Its independent suspension and incredible ground clearance helped the GXV maneuver nicely up, down, and through the off-highway vehicle park's rugged terrain. The 20-plus-inch ground clearance is due in part to the use of front portal axles that house gears inside the wheels. Torque is delivered at the top of the wheel and is transferred down through a system of gears to the center axis the wheel rolls on. The composite exterior of the vehicle features subtle graphics that draw the eye along the exterior lines of the GXV. In addition to this GXV's prowess at navigating difficult terrain, it is fully capable of rolling along at freeway speeds of 70 mph, albeit at a high-ish rpm.
As you might expect, pricing is not for the squeamish. A well-appointed GXV has a suggested retail price of about $370,000. But that means you can rest assured no one else on the block will have one.