Ah ... when trying to slalom mt. Everest you mean ! ... yes, that does pretty much any vehicle.
I still think its something about the suspension - being applied from the other direction than meant to, doing some strange force stuff (and the engine torque in combination). The collision meshes may eliminate that, when they come. (the importer does some basic collision mesh, but when upside-down, it does still fall to wheel level into the ground)