USA road trip in Bentley's GT Speed Convertible Last night it had deposited us in Mammoth Lakes, Mono County, 8,000ft above sea level. As the temperature plunged below zero, deep snow began to cover the sides of the roads. Conditions like these are the last thing you need after a long stint at the wheel, only the GT Speed covers ground so greedily that it didn't feel like a long day at all. In fact, it all seemed like it had gone a bit too quickly. I reflected on how the Speed, as hugely capable as it is, also seemed a slightly confused car. A consummate GT with aspirations to be a sports car, it wants to both run with the hare and hunt with the hounds. It was as if all of the "Speed" bits, the power upgrade to 616bhp, the eight-speed automatic gearbox, the lowered suspension and louder exhaust, didn't really add anything - or at least nothing that this car needed. So, setting off this morning, rather than use the gearbox's Sport setting, which holds ratios for longer and increases the volume of the exhaust, we left it in standard mode. Calmer and quieter should be bywords for Bentley, after all. Even so, as clever as the new ZF-sourced auto is, there's simply no way that a car with 6.0-litre, 12-cylinder engine needs eight forward ratios - no need for any car to change gear five times in two corners. Frankly, if I could afford to spend £167,500 on one of these then I'd quite happily forgo the 15 per cent improvement in fuel economy if it meant it didn't change gear as often. However, while you can pick faults with this car, they are only small. Most important is that, despite its VW parentage, the GT continues to feel like the real deal, from the satnav with its unique graphics, to the seat stitching and chrome air vents, which are just delightful. And then there are the wonderful Bentley eccentricities. The roof is a prime example. It is fabric (albeit four thick layers of it, with 12 panels to hold its shape) rather than metal, not to save weight, says Bentley, but because customers didn't want to compromise the line of the rear deck of the car when it was stowed. And so what if it, along with its various motors, weighs 175kg, taking the car's total kerb weight to 2.5 tonnes? Provided it's snug and draught-free when up (it is), and looks good and keeps you out of the breeze when down (it does), then it's job done. After all, it's not like we're lacking power here. The job of all that power today is to complete the second and final leg of our near-1,000-mile road trip, and it couldn't be more different from the icy climes of Mammoth Lakes. Indeed, if it was warmth we were after, then we'd chosen wisely, for we were pointing the Bentley's dark-tinted chrome grille to the hottest place on Earth: Death Valley, California, where, in July 1913 the mercury reached 56.7C. Our journey through nature's own outdoor oven skirts Yosemite National Park on Route 395. It's sorely tempting to take a detour to visit the Giant Sequoia trees that for more than 3,000 years have inhabited this part of the world. However, notwithstanding the small matter of snow potentially blocking some of the roads, as a resident of the UK I'm clearly still getting used to the scale of things over here, and discover that what looks like a 15-minute diversion is in fact 130 miles away. Plundering the satnav's database for more accessible points of interest, I discover "Half Dome viewpoint," which both sounds promising and is apparently only eight miles off the highway. Better than that, we soon discover that it's accessed by a sinuous and perfectly surfaced stretch of road, providing the chance for the W12 to gulp in the early morning air. Half Dome viewpoint, however, turns out to be a misnomer, for while there's a indeed a very splendid view, it doesn't include the famous silhouette of the Half Dome, which later research reveals is about 100 miles away, obviously... We spin the Bentley round and retrace our route back to the highway, this time with a bit more gusto. The two turbos help to push all 590lb ft of torque through the four-wheel-drive transmission, although the sheer masses involved have the habit of making 600bhp feel fast rather than bonkers. When using all of the Speed's power, you'll also note, with some surprise, that it takes a fraction of a second after lifting off the throttle for the car to stop accelerating, which can send you into corners that bit sooner than you were expecting. Thankfully the brakes and steering (the latter recalibrated to be slightly sharper than a regular Continental GT) are absolutely faithful, if not brimming with feedback. Having briefly experimented on an empty stretch of road to match the claimed 0-60mph time of 4.1sec (it's easy), we continue the long, gradual descent, the temperature climbing as we drop further into the valley. By the time we've reached Furnace Creek (population 24) at 190ft below sea level, the air-con is blowing much needed chilled air into the cabin and even through tiny holes in the seats. Now that's luxury. More amazing even than a car that can chill your buttocks is that plants and wildlife can survive in the harsh conditions of Death Valley. Small shrubs dot the sandy landscape and, at one point, an actual, real life roadrunner does exactly what its name implies and makes a dash for it across our path. The whole place is at once surreal and utterly beautiful. You could spend days examining the rock formations and sand dunes, but our time here is limited and, no sooner have I stopped to slap on another layer of factor 25 than I'm back in the Bentley's cabin, contemplating the contrast that lies ahead. For no road trip in this part of the world would be complete without a finale in sin city. Wonderful, romantic, contrived, ghastly - whatever you think of Vegas, you can't help but be wowed by its irrepressible buzz, not least if you've travelled to it via one of the world's great wildernesses. And, it must be said, in this man-made tribute to money there are few finer ways to hit the strip than in a £170,000 Bentley. Which, conveniently, returns us to our original question. Because with an epic, two-day, 1,000-mile road trip to undertake, especially one where the fuel is cheap and the scenery stunning, it's hard to think of a vehicle as capable as a Bentley convertible. Sure, a classic or a muscle car would be fun, but they wouldn't have the Bentley's excellent ride or massaging seats, and with the roof down you couldn't hear yourself think, let along talk to your passenger in hushed tones. As for which Bentley convertible, there's an argument for taking the entry-level Continental GT V8 and pocketing the £24,000 difference. But such notions of restraint and good taste don't really wash in Vegas. Besides, hitting this town with any change in your pocket could lead a tourist into temptation.