I took my Dec 12 manufactured Diesel 5 speed Grand Cherokee across Fraser Island as my first 4WD off road experience. I lowered the tyre pressures to 18 lb on the ferry on the way over (fitted with Michelin road tyres). Although it mainly pulled through the very deep soft and rough sand competently in low range and on the sand setting, I did lose traction once on an uphill grade on the Eurong to Central Station road across the Island because I reduced momentum too much to negotiate one of the many dips/bumps in the sand tracks/roads. I think the bottom of the car was dragging in the sand mound between the wheel tracks.
i was digging out the sand in front of the tyres to lay sticks for a firmer traction, but the sand was falling in as quickly as I dug it out. I held up 2 tourist buses and other 4WD's, that were scheduled to catch the ferry back to the mainland, so one of the experienced bus drivers approached and advised that digging your way out won't work in soft sand.
He assisted me by taking over the car and reversing out of the situation without any wheel spinning. In doing this the front plastic apron, which was in the sand mound between the tyre tracks, dragged in the sand and ripped off.
After packing the apron in the boot I was able to get traction to drive up the rest of the hill. Without the front apron, electrical components are exposed. After I got past the hill and on to the flat, firmer sand I pulled over to the side to comply with the bus driver's request that he wanted a clear access to catch the ferry. He pulled up his bus behind me and waited for the second bus which didn't come because it also was having difficulties getting traction up the hill.
Previously, I had exceeded the limits of the approach angle, when I drove too fast through a deep dip across the road and dozed into the exit side of the dip and dented the plastic front apron. This was because I was trying to maintain momentum and the car didn't stop.
The Grand Cherokee did drive comfortably and competently along the beach and across the rocky sections of the beach where this was the only access.
After getting home to Brisbane I discovered that I had damaged the cardboard splash protection under the car and also the radiator and of course the front plastic apron. It was about $3k damage.
The message of my experience is that the 218 mm ground clearance is not sufficient to negotiate very soft and rough sand tracks. The Quadra Lift air suspension, only available as an option on Limited and Overland models, would obviously provide an additional 52mm of clearance for these extreme conditions.