The dust is different up here: light and fine, like beige talc in the way it clings to pores, hair, and fleece outerwear. It kicks up easily and hangs in the air, making tight mountain passes even more treacherous. On one side there's a sheer drop-off-no guardrail or even an earthen curb providing a barrier to calamity. On the other side, a sloping rock wall meets the dirt road as piles of sharp rocks-drive too close, and you'll rip up the tire sidewalls. Steer too far the other way, and you'll send a tire off the cliff, attached to a 6000-pound SUV. Not that it's stressful; we're comfortably ensconced in Land Rover's latest-the LR3 TDV6 diesel-humming to tunes on the iPod and trying our best to follow the driving instructor's advice.

We pass by one of the highest vineyards in the world and cut through the vintner's massive estancia. He's been nice enough to leave the gate open for us, but there's no time to stop. We've got important business to attend to: pick up some bread for lunch and drop off supplies-both at a local school.

Along the way, we hit water crossings and bash our undercarriages during some gnarly rock-crawling detours-all fully supervised and improvised by the Land Rover staff. Can't ding them for that, as this entire trip is premeditated; if we really wanted to get to our final destination of Salta, we'd hop on Highway 68 and be there in two hours.

Speed is not the point. Land Rover's objective is to let us experience how well its LR3 diesels do off-road at extreme elevations-and we're getting plenty of both. We've been twisting the LR3's Terrain Response knob periodically, thumbing through the five different settings recommended by our guides. By the time we pull into camp, over 8000 feet above sea level, we're beat and ready for our camp-out under the upside-down canopy of southern-hemisphere stars.