RUTA 40, in Argentina's rural northwest, doesn't have the same ring as Route 66. Nor does it have many paved roads, much traffic, rest stops, road signs or populist mystique. Yet, it is one of the few routes that will take those who use it through a land of extremes -- from lush valleys with century-old vineyards to deserts with blinding dust storms, active volcanoes and the Andes mountains, which pierce the clouds and promise those who test their perilous shelf roads a glimpse of one of the harshest climates on Earth.