The most revered and feared race track in history is the old Nurburgring in Germany. Twenty kilometres long, with 100 corners pitching and rolling through the Eifel Mountains, it was made infamous by Niki Lauda's fiery crash in 1976.
But not even the 'Ring though can compare to America's most challenging race course at Pikes Peak, above Colorado Springs on the eastern fringes of the Rockies.
It might be a few metres shorter than the Nurburgring but, the hillclimb course for the 87th annual Race to the Clouds has half as many bends again (156), has sheer, unprotected cliffs that plummet 1000 metres from the track to oblivion and climbs from around 2800 metres to just over 4200 metres at an average rate of ascent of 7%.
"I had heard about Pikes Peak and seen the famous film shot on the mountain with Ari Vatanen twenty years ago, but only when you come here do you realise how much of a challenge it is," said double World Rally champion but Pikes Peak rookie Marcus Gronholm.
The Finn, and Swedish Rallycross champion Andrea Eriksson, are the two biggest names in global motorsport to attempt the annual hillclimb in two decades.
Names from the past who have come and conquered the mountain include Vatanen, Michele Mouton and Walter Rohrl from the world of rallying and, from the USA, former race hero Bobby Unser.
Since the hill's heyday in the 1980s, more and more sections of highway to the summit have been sealed. Within two years the whole road will be asphalt.
For Gronholm, attacking the mountain in its natural state is an opportunity too good to miss. "This is one of those events that will be great to tell people you came and did."
Gronholm and Eriksson's weapon of choice to try and break the back of this mighty mountain is an 850 horsepower, four-wheel drive Fiesta based on the top-selling road car in Europe, which will go on sale in North America next year.
"The car is way more powerful than a World Rally Car," explained Eriksson during one of the three dawn practice sessions for the race. "The altitude sucks out almost 30% of the power by the summit so it is best to come with plenty. Traction is the other key thing and so we fit huge wings to keep the car fixed to the mountain. It is no place to go off..."
Practice was a challenge for the two Scandinavians. Eriksson slid wide in the Boulders section near the summit, slamming the Fiesta into a rock. It took two days to straighten the car in time for Sunday's race.
"I lost power into the corner. And without power you lose some control. I tried to stop the car with the handbrake but unfortunately was one of the few corners with rocks on the outside. The car rolled onto its side, which left it and me with a few sore places," he said.
Meanwhile Marcus Gronholm requested a change to the set up of his gearbox in search of better acceleration out of tight corners and after the final practice the team decided to put a new motor in the car.
"The previous one was overheating a bit, so it was sensible to change the engine," explains team leader Eriksson.
In one year, 1994, the record at Pikes Peak dropped 39 seconds - as fast as a rock falling from one of the precipitous cliff edges. But since 1994, the record has only crept down by three seconds. Now it sits precariously balanced on the edge of the 10 minute barrier, and is currently held at 10m01.41s by Japan's Nobuhiro 'Monster' Tajima who is back in 2009 to defend his title and, like the Ford drivers, try to break into the nine minute zone.
"To break the 10 minute barrier on our first attempt is quite a challenge," warned Gronholm the night before the race. "But, hey, I like a challenge..."
Weather forecasts are trash before they are even broadcast in the Rockies. Some years, the hillclimb has started in 30 degree heat and finished in a -10 degree snowstorm.
Wary of predicted afternoon storms, Monster Tajima opted (as current champion) for the Unlimited Division, including the Fiestas and a modified Group B Ford RS200, to run before lunch.
Britain's Mark Rennison, in the RS200, missed all of practice with a broken engine. But he was ready to fight for honours come race day. With no experience of Pikes Peak, his time of 12 minutes 11 seconds was very respectable.
"I'll be back hopefully and give this a good crack," said the former rallycross champion.
Next up was Andreas Eriksson. His damaged Fiesta straightened, he launched off the line with gusto. The crash earlier in the week meant he had not practised the first section of the course at speed, and so, caught out at Engineer's Bend, a third of the way up, he lost control and crashed the Fiesta.
All eyes now rested on double world rally champion Marcus Gronholm. A new engine up front in his Fiesta, the Finn knew he had to deliver.
"The car has been at its best on the first section and was today," said Gronholm. "It handles so well on the sweeping tarmac. But it was clear from the start we had a little misfire. I pushed on regardless and by the mid section I was hopeful of a good time. Not a record time but a reasonable one."
As Gronholm neared the final section of dirt highway near the summit, the turbo failed, and the interior of the car started to fill with smoke.
Undaunted, Marcus pressed on to the peak, left-foot braking to keep what power remained on tap. But the brakes too started to feel the strain and as he crossed the finish line, just over 11 minutes since the start, flames erupted from the wheels.
"With no turbo it was game over," said Gronholm. "It's a shame. I think we could have managed a 10 minute 40 second time. We'll just have to come back next year. This car has huge potential."