• This is the third of a three-part series covering the development of the Porsche Cayenne sport utility vehicle. This report covers the final development drive in the summer of 2002 across the American West. Any severe problem on this trip would force a delay in the start of production.

Development of the Cayenne has taken the Porsche test team from closed racetracks in Germany to ice-covered lakes in Sweden and snow-covered roads in northern Canada, to the desert sands of Dubai and the stark harshness of the Australian Outback, to the rocky mountains of Spain and now, for their last pre-production evaluation, to the Rocky Mountains of the United States.

Led by Peter Hass and Juergen Kern, Porsche's own Lewis and Clark - though they'll tell you that they're more of an Oscar and Felix Odd Couple - the corps has spent three years exploring the Cayenne's components and its capabilities on and off pavement, in real-world conditions, though sometimes at unreal speeds.

"This is the final test, to decide whether we can offer this car to customers or not," says Klaus-Gerhard Wolpert, director of sport utility vehicle operations for Porsche AG. Wolpert and Cayenne project manager Egon Verse (who also was project manager for the development of the Boxster) have joined the test team for a few days so they can return to Germany and assure Porsche's top management that the Cayenne is ready to go into production.

Wolpert, who oversees both the vehicle's development and its production, explains that the Cayenne team's task was to make sure that an SUV "fits into the Porsche brand, and that it's what Porsche customers want."

The pressure to achieve those goals has been on the Cayenne designers and development engineers, and now rests again with the test team, especially on this, the final examination before the start of production. The mission is what the Germans call "Erprobung," a proving test, a trial to verify the Cayenne's worthiness.

After logging miles through the American desert, climbing slickrock in Utah and crossing the Rockies on paved highways and rocky trails along mountain ledges, Wolpert is confident that the Cayenne "fits perfectly."

Wolpert explains that to be a real Porsche and also a real SUV, the Cayenne had to be the best SUV on pavement and one of the very best off road. "It is very hard to bring these extreme positions together," he admits. But then he points with pride to the fact that a vehicle that has lapped the Nurburgring just as quickly as the Boxster S (and, adds Verse, ranks in the top 10 among all pre-production cars in testing at Germany's Hockenheim race track) had just followed an industrial-strength Hummer H1 up steep slickrock in Utah, and had done so while wearing high-performance street tires, not special off-road tread. "The only limit," he notes, "is ground clearance and ramp angles."

But the Cayenne's ground clearance and approach, ramp and departure angles were more than sufficient a few days later on a morning tour of the Corkscrew Gulch Trail and adjacent and ancient mining roads that climb out of Silverton, Colorado, and provide precarious vantages but spectacular views of the dramatically colored Red Mountains and other alpine environments.

"This route is moderately difficult to drive because some sections of the road are rough, steep, and narrow, and there are several sharp switchbacks to negotiate," write the authors of 4WD Trails of Southwest Colorado, who rate this trek a 4 ("high-clearance 4WD recommended… rocks larger than six inches possible, but a reasonable driving line available… substantial sections of single-lane shelf road… stream crossings less than fifteen inches deep…"). The scale goes from 1-10. Graded dirt roads are rated 1, by the time a trail earns a 5, the authors recommend only experienced off-roaders proceed.

Wolpert says that while few Cayenne owners may venture off pavement very often, "It's important for customers to know this car is very good off-road."

He compares it to the confidence that a 911 Turbo owner has, the knowledge that because their car is "born of a racecar," it is capable of phenomenal performance on road or track. "The 911 Turbo owner knows that 'if I go to a race track, I could drive it'," Wolpert says, "even if they never do."

The Cayenne test team has explored on-road and off during this final pre-production trial. The route started in Los Angeles and then took the team and various Cayenne managers through Death Valley, across southern Nevada and Utah to Moab, then up across the mountains of Colorado, and finally down through New Mexico and - 4,000 miles after the start of this trip -- on in to Phoenix.

At least that was the main phase of the test. Some of the Cayennes and engineers already had driven from New York to Los Angeles to do on-board diagnostics testing and to meet with CARB, the California Air Resources Board, to discuss future emission regulations (even though Cayenne production is just beginning, the development team's work doesn't stop). Another group had driven from Denver to Seattle and then to San Francisco, doing engine control unit checks.

And after this test, a two-week on-board diagnostics test will be held in Los Angeles and there will be a 100,000-mile EPA run at a test track near Phoenix.

The main caravan includes seven Cayennes - 334-horsepower 4.5-liter V8s and 444-hp 4.5-liter twin-turbos -- a BMW X5 that serves as a best-on-road competitive benchmark and rented SUVs to carry tools, spares and support personnel. Five of the Cayennes are pre-production vehicles - so-called "00" cars in the countdown to cars for customers -- fresh from the new factory assembly line at Leipzig. The other two are six-month-old prototypes - "PP" in Porschespeak -- one equipped with a more extreme off-road package that's still in development, the other testing potential options for the rear climate control system.

But the emphasis is on the factory-built or "00" vehicles, which show much better fit and finish and NVH control than the "PP" versions. The point of this test is to make sure there are no problems that might delay the start of production. To do that, the team pushes the Cayenne to its limits, even while stuck in Denver's morning rush-hour commuter traffic.

Pop! The sunglasses case in the overhead console opens. Wolpert reaches his fingers as far inside as they'll go, feeling for any sharp edge that might scratch a lens. Then he closes the cover and pushes against it hard, again and again, checking both its firmness and its flexibility, taking notes when needed. Then he moves on to other switchgear, poking and prodding everything he can reach from the driver's seat.

When it's suggested that children do the same thing the first time they get into their parents' new car, he says that's exactly the point: "If you have a new product or a new car, you use it," he says. "Like a small child, you play with it."

But developing a new vehicle is not child's play. Not counting bolts and other fasteners, Wolpert says the Cayenne comprises 5,500 parts that had to be designed and tested, tested not only for their own qualities but for how they work with all of the other parts, and that especially applies to the vehicle's electronics.

Getting special attention on this drive is the Porsche Communication Management system with a large color monitor that displays audio, on-board computer, navigation, HVAC and other information at the top of the center console. A glitch has been discovered in the connection between the PCM and the smaller readout that appears on the instrument panel in front of the driver. Porsche believes such redundancy is important, that the driver shouldn't need to divert eyesight too far from the road, especially at autobahn speeds. New software is being written to address the glitch. Also being fine-tuned is the software that automatically shifts the PCM screen from daylight to its night light setting.

The Cayenne has 40 electronic control units that communicate not only with their own specific components, whether engine management, airbags, navigation system or the power sunroof or seat controls, but with each other through a data bus system.

Elmar Kloesters is vice-project leader for the Cayenne's electronics, and explains that when you're reaching for the highest result, "it takes a lot of big things to reach the ceiling -- engine, powertrain, chassis -- but the last three centimeters is electronics."

And that last three centimeters is crucial, and is time consuming, and such last-minute details are not unexpected at this phase of a vehicle's development.

"The most time consuming thing," Kloesters adds, noting the many layers of software through the vehicle, "is to test them with each other, to make sure a software change with one unit won't affect the software in another.

"Sometimes it takes time for problems to show up," he adds. Just as with any other component, "You test on a test bed and then on the car. We test most software for 300,000 km (nearly 190,000 miles). After this test, some of the cars [as well as Kloesters and other engineers] are going on an extra 100,000-km (62,000-mile) test to validate the software we just fixed."

While off-roading, a problem was discovered in the software that enables a smooth transition from low range back to high. New software was written, and while trail boss Peter Hass leads the main group on through Colorado and New Mexico, Juergen Kern and others detour to a test track in Arizona to begin evaluation of that new software. It's like Lewis and Clark splitting at Traveler's Rest, seeking to make the best use of their available time as they headed home.

For the test team, it's a familiar cadence. Such extensive testing means long days for the engineers, but Kloesters contends that's a good thing because it means that just like a customer, the team drives in all weather and road (and off-road) conditions. Just like a customer, eyes get tired and are bothered by glare that can't really be duplicated in a test lab, all the better for making sure headlamps and interior and instrument panel lighting meet real-world demands.

Porsche engineers repeatedly stress the value of the extensive real-road testing they do with their vehicles. One engineer notes that if you test primarily on a corporate test track, you end up building a vehicle that's ideal for that track, but may not be ideally suited for the variety of roads and conditions drivers will face after they buy that vehicle. Kloesters explains that Porsche engineers sometimes take well-disguised prototypes home for the weekend so they can do even more real-road evaluations, and to see how the car - especially an SUV -- adapts to actual use by a real family.

However, such testing risks exposing the Cayenne to the prying eyes of spy photographers, so until this final test drive in the American west, the Porsche SUVs have worn heavy monotone camouflage. Even here, showing their true colors - silver, black, a really dark green and a burgundy shade among them -- for the first time on public roads, they still wear no badging and have taped masking around their head and tail lights and a taped triangle that runs from the rear wheel arches to the tail lights.

Still, no one at an off-road center where the team stops for coffee and snacks in Silverton had any inkling that they were Porsches.

After leaving the Corkscrew Gulch Trail and turning south on Colorado's famed "Million Dollar Highway," Route 550 that winds through amazing mountain scenery between Silverton to Durango, the Cayennes are caught by the driver of a Porsche 928. He leapfrogs around - no easy task on this stretch mountain road. When the Cayenne caravan reaches Durango, the 928 pulls into the same service station where the Porsche team stops to refuel. The sports car's driver is certain that the SUVs are a hot-rodded, next-generation version of the X5, and asks if he can look under a hood to see if they're powered by the M5's V8.

I wonder how, with the Cayennes so exposed, that he doesn't recognize them as Porsches. Although they have tall front fenders and high-mounted headlights, the shapes of those components mirror the 911's. Also apparent are the 911-style hips that widen smoothly from the base of the D pillars. The Cayenne is not a slab-sided SUV, and although it is a tall vehicle, it takes a sports car-like stance that hints strongly of its on-road capabilities.

With the exception of perhaps only the youngest of the Cayenne engineers, everyone on the test team is a Porsche veteran whose primary experience is with the 911. But while their hearts are in sports cars, they know the Cayenne faces unique challenges and they are diligent to see that the vehicle is ready for all of its tasks.

Thus, after early testing with ventilated disc brakes, the Cayenne goes into production with solid discs. Guenter Aydt, who has been engineering Porsche brakes for 22 years, explains that the test team discovered while off-roading that small bits of gravel could become lodged in the ventilation holes, causing damage to the discs and brake pads. That could affect brake wear and performance, things you want to avoid when stopping a 5,000-pound vehicle capable of speeds of up to 165 miles per hour, or when Porsche Stability Management shows its off-road capabilities by safely taking you down the steep slope of an off-road trail.

After being part of the team that developed PSM for the 911, Michael Pfeifer led the group that adapted the computer-controlled stability technology for the Cayenne's special requirements of on- and off-road capability. On an earlier trip in the Australian Outback, he'd demonstrated how PSM keeps the Cayenne calm even in 90-mph, lane-change emergency maneuvers. Now he's just as pleased as he sits behind the steering wheel as PSM coordinates with Porsche Traction Management, the Cayenne's four-wheel drive system, and enables the vehicle to slowly and calmly wind down the steepest sections of the Corkscrew without the driver needing to push any buttons, or even to touch the brake or gas pedals.

Pfeifer is proud of the way these technologies work, but now he's just as proud of his new responsibilities, in total quality management. On this trip, he manages the traffic light, the list of problems that the team discovers. Obviously, the goal is for every problem to become a green light, which means production is a go.

"A few months ago we had a few red lights," he admits. "Now there are no red lights, a few yellow [like that new software], but they are manageable."

But there's much more to it than red, yellow and even green lights. Noise, vibration and harshness issues may not stop production, but they are important to the test team, so important that Pfeifer rides prone in the cargo area for many miles on a rough gravel road, trying to discover the source of a noise he didn't like.

Maybe he just should have asked Hans-Jochen Stark, or "Hi-Oh" to his friends and co-workers. Even veteran Porsche engineers consider Stark to be something of an acoustics superhero.

"It's not just acoustics. It's noise, vibration and harshness," Stark explains, emphasizing the word vibration.

"The feedback from the car is very, very important. It has to have a solid feeling," he says, explaining that a driver's torso is particularly sensitive to low-frequency vibrations, such as those in the 5-15 Hz range. "The car has to feel as if it's one block, not just a bunch of components. It's our job to get this feeling."

Stark says achieving this solid feeling starts with the engine and the way it's mounted in the car, and extends throughout the drivetrain and the suspension, and adds that this process is made extremely more complex by the Cayenne's dual nature as Porsche and SUV.

"It was not easy," he says, noting the expense of developing new hydro mounts that won't be destroyed by the rigors of off-roading. He also talks about the fact that when the powertrain and chassis are so well controlled in terms of NVH qualities, other issues can become more apparent, such as tire noise or wind rush around exterior mirrors. He notes that the Cayenne's window sealing system is not twice but three times as expensive as the industry standard.

"Sometimes," Stark says, the NVH group isn't the most popular within Porsche, because when it finds problems, "it's work and money you have to spend." But, he adds, "We do it together… to solve the problem."

Meanwhile, Stark says that what others perceive to be his amazing hearing is the result of training, and is more a sense of feeling than of hearing.

Stark joined Porsche right out of college, in 1984, and his first job was what many consider to be a dream job -- test driver at Weissach, Porsche's research and development center. After nearly half a dozen years of experience as a test driver, Stark moved to suspension engineering, and then into NVH control, working not only on Porsches but on projects for other automakers. Often he says, those other auto companies came to Porsche for solutions to things that hadn't been issues in testing on their own proving grounds, but became obvious problems when they ventured onto real roads late in the development process.

"Do you feel that?" Stark asks as we ride though Arizona's White Mountains, near the area so devastated by forest fires this spring.

Actually, the Cayenne Turbo feels just fine from the passenger's seat, and even from the back seat, which I've also tried (what I really want to do is to drive, which must wait for the vehicle's official press launch). But Stark detects a subtle vibration in the drivetrain within a very narrow speed range, a vibration that he doubts very many customers would even notice. But he takes the car back to that speed and this time has me reach over a take a light touch of the steering wheel, and now I can feel a low-grade vibration.

Apparently never satisfied, Stark also will talk at the nightly engineering meeting about some shift shock he detects (most likely just a small software fix, he's sure) and he thinks there's still room and time for a slight tweak of the air suspension mounts.

"But when we get back to the office," he says, "they will ask 'how was your holiday?"

Driving through the American west can be a wonderful experience, but there was no time for the Porsche test team to visit the Grand Canyon or to ride the famous narrow gauge railroad from Durango to Silverton, or to trade Cayennes for horses at a dude ranch.

Still, the test team doesn't mind such teasing about its holiday trips, because it finds its work rewarding, and on both professional and personal levels.

After months of super-secret test drives at secured tracks and under the cover of heavy camouflage at remote locations around the globe, Michael Pfeifer finally took a still disguised Cayenne home for the weekend.

"Daddy, I thought we were driving an off-road vehicle," Pfeifer's 7-year-old son, Christoph, said from the back seat as they hustled along a road that wound through hills in the German countryside.

"We are," said Pfeifer.

"But you drive it like a 911," his son insisted.

"This is a Porsche SUV," Pfeifer replied.

"Oh," his son responded with a knowing smile.

"This was a very proud moment for me," Pfeifer said in retelling the tale. "He could feel that the Cayenne was a Porsche."

And that's been the point of all the work by Pfeifer and everyone else on the Cayenne development team: To make sure that this sport utility vehicle really is a Porsche, and that this Porsche really is an SUV.