In order to prove the mettle of their Cayenne models, Porsche entered a scad of them in the TransSyberian rally from 2008 to 2010, and won all three of them on the trot. In order to celebrate these victories, they built a limited edition off-road oriented Cayenne S for street use in 2010, called the "Cayenne S TransSyberia". An original name, I know... This is the perfect Porsche model when you need to head for the hills while the shit hits the fan around you. Say, for example, the collapse of your country's geopolitical landscape.
Each of these special models was fitted with air suspension, active suspension management, the Cayenne GTS' slightly uprated 405-horsepower engine, stainless steel skid plates front and rear, and a lower 4.11:1 final drive ratio for superior off-roading prowess. Finding one with the optional "off-road package" is key, however to properly bugging out, as this kit includes a locking rear differential, rock rails, a reinforced "engine bay guard" and reinforced protection for the fuel tank and rear diff.
Granted, the TransSyberia was limited to just 600 examples for North American consumption, and they carried a whoping $70,800 base price when new. That price has fallen a bit, but as they are rare they carry a premium over a standard Cayenne. These do occasionally pop up on eBay, and the prices have varried wildly, but generally expect a decent one to fall somewhere between $30,000 and $50,000. These cars are quite comfortable, even as you're bounding across open plains, or crawling over some rocky mountain passes to get away from the rest of the world.
If you do buy one, or you're one of the lucky few to already have one, don't forget your portable solar panels, gas masks, and 2-year supply of canned food on your way out the door! Good luck out there.