Dead Heat

"My face! My face! My face! My faaace! It's burning my face off!"

"Morning, Justin. Is it a bit hot out?" I ask, smugly clicking the Merc's A/C up another chilly notch.

"No, you idiot. It's actually burning my face. My actual face. It's been burned. By this!" I flinch as Justin presses a bulky black camera into my hands, and then yelp at its temperature. It's like it's been pulled fresh-baked from the oven. And there's a red mark swelling up in the lower orbit of Justin's right eye socket. Turns out that after a few minutes of sunbathing, the body of Justin's camera has heated itself to such a degree that it has indeed had a go at flaying his almost-transparent British skin and the rubber eyepiece has become Blu-Tack tacky.

"What's the temperature reading?" asks Justin, prodding manfully at the meat of his cheek and trying to lie his entire body across the pair of air vents on the dash.

"Er, current air temperature is reading between 129 and 130 degrees. Fahrenheit." I add, somewhat unnecessarily. "But according to today's news, the ground temperature on the salt pan to our left should crest 180 degrees. Which means we should be able to roast your whole head by about 4 p.m."

Justin says nothing. Just leans over, pops open my door and shoves me out. And I meet a record-breaking July in Death Valley head on, face first.

The first breath in this type of temperature is like trying to swallow hot cotton wool. It catches in the back of your throat, clings inside your lungs like the air itself wants to stay in the shade. Gasping is not a good idea, simply because you begin to suspect that the air coming out of you is actually slightly cooler than the air going in. And it's dry. Dry as death. Not the sweltering heat of the tropics, where the sweat emerges to melt you away. Here, you sweat purely to try to dissipate heat. You feel the sweat prick open your pores like a cracking dam about to burst.

We should be more prepared. Actually, I'm beginning to suspect that limiting our preparation to buying two large hats and two bottles of water to be somewhat stupid.

"We should have brought bigger hats," says Justin, from inside the car. "And more water. And some grown-ups." I look down and realize that my phone doesn't work. "We're going to die here," I say quietly, and probably somewhat melodramatically, seeing as we've only been here two hours, and there are seven tour buses about 50 feet away.

It's easy to see why car manufacturers hot-weather test here. Temperatures in California/Nevada's Death Valley regularly crest 113 degrees, and if you come in the height of summer, as we have, every breath feels like you're sucking on a superheated bong. If your car is going to suffer a heat-induced failure, then 130 degrees is likely to find it. To push the limits, we've decided to try a little economy test on something a bit special. The Mercedes SL63 AMG — currently the world's most powerful naturally aspirated V8. The test involves driving a 400-mile route around Death Valley without filling the car up with fuel. No problem, you may think, until you realize the car has a 25-gallon fuel tank, and the best you can expect is roughly 20.3 mpg (combined), according to Merc's own figures. That gives us a range of 419.804 miles, not including photography miles, A/C set to freezer burn and driving like your life depends on economy. Which, rather unironically, it does.

The problem is that the big SL is a bitch to drive slowly. The 6.2-liter V8 loves to rev in a very un-Merc-like way. Add to that the new MCT-7 Speedshift semi-auto manual gearbox that shifts both like a paddle-operated manual and a torque-converted auto depending on your mood, and you'll struggle to find reasons to dawdle. On the way here, on some very deserted roads, the 4.6-second 0–62-mph time was within gloriously noisy easy reach, and the 155-mph limiter all too easy to graze. But as Las Vegas recedes, we arrive at a small town called Shoshone, brim the tank and prepare to adventure.

In reality, we prepare by stopping for food. After refried beans in what amounts to a roadside sauna, and a chat with a charming yet completely incomprehensible waitress, we're off, having purchased Justin some boots more suited to the back country than his stylish but somewhat retarded choice of Tod's English brogues.

We fire up the SL, drop the roof, don recently purchased palm-leaf stetsons and head off into the Valley of Death like a pair of rich, suicidal idiots on a tremendously gay holiday. And, for a while, it's fine. We drive conservatively, and burble gently between vicious, primeval rock faces seemingly vomited from the desert just moments before. Great, fleshy pink walls that melt into watery-looking salt pans via the medium of a heat-haze that stands about six feet high. The temperature gauge on the SL creeps ever higher. After a couple of hours of paranoid satellite navigation that somewhat ominously insists we make a U-turn at the nearest available opportunity, we stop near a place called Badwater to take stock.

Badwater, unsurprisingly, is literally named. Back in the day, what mule-mounted pioneers originally thought was a not-often-seen oasis, turned out to be a stream of water that had run through the endless salt pan. It was so heavy with salt and heavy metals that no one could drink it without instantly falling down dead.

Cracking open the SL's doors — we've long since abandoned going topless, thanks to a worrying redneckedness — brings a wash of heat akin to opening the door on a pie oven. The SL has been trotting along with nothing but a couple of gurgles to signify the gradual ramping of the heat gradient. Though it has to be said, we're only 100 miles into our journey, and we're already a smidge under three-quarters full. Which doesn't bode well.

What is apparent is that although the water temperature of the SL has only inched its way up by a fraction, the car is now idling some 600 rpm higher than it was back in the relative coolness of our 100-degree parking garage. It's breathing harder, working more, just to keep itself cool. But set against a temperature gradient that peters out rather than drops off, the SL is obviously finding it hard. And we've got a long way to go.

After a few minutes of marching around, we decide to move on, mainly because this isn't like the desert nearer to Las Vegas. This isn't like any desert I've ever been in. Usually there's a small background hum of life — the little clicks and knocks of vitality that come from insects or birds, even if you can't see them. But there's nothing here. No life. No heartbeat. For sheer lifelessness, the only other place it feels like is the Arctic. All that's here is the flaying wind and the ever-present, soul-destroying heat. And it's eerie. The Merc, however, just sits like a jewel, glinting. If there was a car to capture your imagination in such an ostentatiously natural panorama, it's a bright-red, brand-new Merc SL. All angles and planes and snarly face. It fits. If you're going to travel an epic place, you might as well have an epic ride.

Justin, meanwhile, is back in the car and trying to chill his cameras with the air-conditioning in readiness for a foray outside to take some pictures. The camera batteries, weirdly, are also dying, their chemicals interfered with by the extreme heat. But hit the button, and the SL thumps into life with dull regularity. If we're looking for a breakdown, then we're unlikely to find it within the relentless brilliance of the SL's engineering. But we may find it in the relentless march southward of the SL's fuel gauge. While sat here on idle, it's dropped a fraction of an inch on the dial. I do some rough calculations and reckon that the SL, which is now idling somewhere near 1,700 rpm, is revving at the same rate as it normally would on a 70-mph cruise. Except we're not moving. Which is shit mpg, if you think about it.

Cue strained and feather-footed driving, and an atmosphere that wavers between hysterics and thoughtful silence all the way through Furnace Creek and up to Stovepipe Wells, with several stops for pictures. We really are running out of fuel. The SL is reading 15.8 mpg, though there is some confusion as to whether the American gallon means that we're doing better or worse. Either way, we seem to be screwed, because the differences simply mean that we'll be slightly closer to our destination when we die. At the halfway point, our range sinks to just 110 miles. With 204 miles left to travel.

At this point, it would be nice to say that some skillful driving brought our range marching back up the dial to the point at which we could manfully make a play for glory. That somehow, with the dusk slowly approaching and the heat of the day significantly failing to relinquish its stranglehold, we pushed on through and made it back to Shoshone in the nick of time, with zero miles in the tank and somewhat fried nerves. But when we meet a park ranger, the vague idea of injecting even more jeopardy into a trip with only a tenuous grasp on sanity suddenly disappears. "People die out here," he says, pointing at our pitiful supply of water. "This ain't the sort of place you take risks for the hell of it. And if you drive any farther into that side road, you ain't coming out. Have a nice day, now."

With that, he scuffs up some dust with his 4x4 and tramps off into the burgeoning night. No offer of salvation, or pointers for nighttime survival, just the bare facts. We have now gone past the point of no return, and we can't actually get back to any of the fuel stations we've passed. Which means we have to press on to the next town and hope we can get fuel. Glory be damned, I'd rather just be somewhere with some sort of shelter before we have to leave $193,000 worth of Mercedes to the desert winds. Inexplicably, Justin decides now is the perfect time to start doing complicated rig shots. Burning fuel. Shortening our lifespan.

Finally we get moving, roof down — figuring that at the slower speeds we'll be traveling, the aerodynamic trade-off is better than having the A/C on full whack — and are treated to some of the most jaw-slackening scenery in the world. Death Valley, at dusk, is a heart breaker. Not the lush vistas of the rainforest, the majestic spiky teeth of a European mountain range, nothing that complicated. But big swathes of rock and salt, even the plant life reduced to small, aggressive, punky little growths. This is hard country, but that innate harshness frames a part of the world that, when you see it at the right angle, becomes as beautiful and stark as anything on this planet.

The atmosphere in the car, on the other hand, is tight, cringing. Not the usual bravado. As the fuel drops ever lower, we see signs for the nearest fuel stop: 40 miles. We have 40 miles showing on our range. Cue nearly an hour of pulse and glide driving, some of the most cost-conscious piloting I think I've ever done. Even if we miss by a couple or three miles, that might be enough to make things very, very uncomfortable — and both Justin and I are all too aware of that fact. And, with five miles showing, we make it.

To a closed fuel station.

"You have to be joking me," I say, envisioning sleeping in a small car, in still 95-degree heat, with an already grumpy Justin, who smells of refried beans and sweat. "This cannot be happening. No. Nonononononononononononono."

And it's at that point that Justin finds the one pump, at the back, that takes credit cards. I could kiss him, properly, with tongue. And just like that, all the tension is gone. Washed away in a flood of cool relief. We fill up and head back to Vegas, the cold neon and air-conditioned utter fakery of Vegas, finally arriving at 5 a.m. Turns out there's a reason that Merc sends people out here to do so much hot-weather testing; it's so that we don't have to. And if you're planning on running economy tests in the world's hottest place, with the world's most powerful naturally aspirated V8 engine, you don't just need a bigger hat. You need a bigger fuel tank, too.