The glossy guidebook has failed to mention that the rite of spring in Argentina is a lonely affair. Forget the spring of Walt Disney or Animal Planet; though the chill has left the thin Andean air, life apparently hasn't returned to these rugged lands. Aside from some prickly bushes and Joshua trees, a few goats and vicua (think small llama), there seem to be no other living creatures save us and our team of handlers.

They're a motley crew of off-roaders and adventure junkies, mostly former Land Rover G4 or Camel Trophy competitors who travel the world helping with demos and dealer training. These are salt-of-the-earth fellas, all incredibly competent and genuinely friendly-despite having the unenviable task of riding shotgun with us offroad novices. I can't fathom how they're able sit on their hands and quietly suck in through their teeth as we rookies stumble through this spectacularly treacherous terrain.

Head instructor Bob Burns informs us that, for every thousand feet of elevation we ascend, the LR3's 2.7-liter common-rail turbodiesel loses about three percent of its power. By the time we hit the summit of our journey, the LR3's 188 horses will be cut by more than half.

It's already starting to feel sluggish as we begin our assault on Abra del Acay-the highest pass of Ruta 40. Throttle response is wheezy; matting the pedal induces a several-heartbeat delay before the turbo churns faintly and acceleration halfheartedly proceeds. The wait is even longer if you're looking for an automatic downshift.

Yet it doesn't matter: We have torque to spare and are in no rush as we snake back and forth up the switchbacks, looking for signs of life amidst the prickly scrub brush and lunar landscape. Almost everyone in the convoy, human and vehicle, is suffering from the altitude. A few more seriously plagued by altitude sickness have already headed down to Salta via the highway, while the G4 Challenge support LR3s, with their gas V-8s and heavy loads of gear and equipment, are laboring harder than the diesels.

Most of the trip so far has been T-shirt and jeans weather, a slight chill in the shade but springtime warm in the sunlight. At the summit, it's more like being inside a blast chiller-turbulent, loud, and chicken-skin cold. One of the instructors screams that the wind must be blowing at over 60 mph. At least, that's what I think he says.

Despite the wind, the landscape below our feet is magnificent. We're at 16,059 feet above sea level, but it doesn't look that high because all around us are craggy Andean mountains of similar height. It takes the cold, swirling air, and whiter, brighter sun to remind us how high we really are.

A few in our crew are giddy at making it to the top and ignore the warning about running around at altitude. They'll pay for it later, with headaches and oxygen tanks. We pose for some photos and take in the scenery with shallow breaths, before piling back into our LR3s. We're an hour away from our hostel in San Antonio de los Cobres, and there's only about as much daylight left, so we must make a hasty descent. Navigating rock-strewn roads using headlights is no fun.