The route: 270 miles across America's great Smoky Mountains
The car: a £50,000 BMW X5 4.8i SE
Test-driven by: Vicki Butler-Henderson, presenter of Fifth Gear
One of the things I love about hitting the open road in the States is those hulking trucks and their trailers, the old-school pick-ups and gas-guzzling, folksy cars. I love American juggernauts; all that glistening chrome and those fearsome engines. I'm cruising through Greenville in South Carolina - one of the most rural states in the Deep South - en route to my hotel. And the sight of them, plus the warm breeze and heavy air, makes me feel like I've really arrived Stateside.
I'm here to drive in the Great Smoky Mountains National Park, which sits astride the North Carolina border, amid the southern climax of the Appalachian Mountains. The most visited of America's numerous national parks, it draws more than nine million adventurers and sightseers each year, and one of the best ways to experience it is on wheels. Its 270 miles of mostly paved road are perfect for driving in 4WDs - as many American families have done before me.
The landscape is classically American: rugged mountains; tumbling streams; weathered clapboard buildings from the 19th century that make you think of The Little House on the Prairie; tracts of old-growth forest, views of undulating ridges draped in hazy blue tendrils of fog.
I'm excited because I'm going to be driving the Smokies in the new BMW X5, a £50,000 top-of-the-range 4.8i SE (rather than the cheaper, more frugal 3.0-litre diesel option). It's a more hulking beast than the one it replaces, in every dimension, but still perfectly proportioned, and it hasn't lost any style in its remodelling. The main news is that it can now carry seven people, thanks to an extra set of child-sized rear seats. Perfect if I were taking kids on my great American journey.
The original X5, launched eight years ago, kicked off the whole Sports Activity Vehicle or SAV market. The X5 has always been my favourite, because it handles with the dynamism of a sports car - an admirable quality considering it sits so high from the ground and weighs as much as two Ford Fiestas. I'm keen to get this machine on the road and see what it can do.
Armed with more maps than a map shop, I venture onto Route 101 and head north towards the Great Smoky Mountains. And I notice that even the X5 seems quite slight compared with the real gas-guzzlers sharing this three-way interstate. I'm a speed demon and am tempted to bury the throttle and see what the 355bhp V8 engine can do, but I'm held back by road signs that warn of the 55mph speed limit, and by my just-discovered knowledge of the "school bus rule". It's this: if a stop sign pops out from the driver's side of one of those iconic yellow school buses, then you must stop, no matter which direction you are travelling in.
The upside of the 55mph speed limit is that it gives you a chance to take in the gentle South Carolina scenery, which is soft and verdant. The main crop they grow here is peaches, and dotted along the road are realms of tatty old hand-written roadside signs advertising their juicy virtues. The 101 takes me towards the border with North Carolina, where I peel off onto the 276 road and head for Caesars Head at the edge of the Pisgah National Forest.
It's a twisty, two-way road that carves its way through millions of tall trees. But I'm distracted from the majestic scenery by the embarrassment of gadgets inside the car. In general, I detest aids, but the Active Steering, Dynamic Stability Control, Dynamic Traction Control and Cornering Brake Control don't deaden the connection I feel with the car. I drive on up towards Caesars Head and Cedar Mountain, passing signs that read: "No litter. $1000 fine. Prison". They're keen for you to keep to the rules around here then.
