Porsche built the first-generation Cayenne to prove that an SUV could simultaneously offer excellent driving dynamics and real off-road capability. Unfortunately, the complexity of a big Porsche with a wide range of engine options, an Aisin six-speed automatic transmission, a transfer case with a locking center differential and true low-range all-wheel drive, plus options like air suspension and electronic disconnection of stabilizer bars resulted in significant depreciation of facelifted 955s and 957 Cayennes.
The depreciation curve, however, allowed me to buy a 2006 Cayenne Turbo last fall, at pennies on the dollar. From the outset, I had planned on making a few light modifications in hopes of turning the SUV into a lightweight, ski-season storm chaser, with additions like Toyo Open Country A/T III knobby tires, a skid plate from Eurowise to protect the dry-sump twin-turbo V8, and a swiveling rear spare tire and gas can holder.
My to-do list continues to grow now that I recently took the Cayenne down the Mojave road to test if Porsche’s original super SUV could conquer the relatively technical climb of Paiute Ridge, a road I had previously explored in both a Jeep Gladiator Rubicon and my own 1998 Mitsubishi Montero.
Ventilate a little in the name of science
In my Montero, I needed to engage my locking rear differential to climb some of the rockier sections of Paiute Ridge. But I made this trip without an air compressor, so I never aired the LT-metric Cooper Discoverer S/T Maxx tires. So in the name of science I felt compelled to lower the Cayenne’s Toyos to the same 38 PSI I’m using the Montero – just a little less than my usual 42-48 PSI for ideal fuel economy and reduced road noise from the P-metric tires. All Cayennes equipped with air suspension include an integrated compressor, making it easy to ventilate after off-roading. So on an earlier trip to a milder section of the desert, I aired even lower.
Route planning with OnX Offroad
I also used this adventure to test the OnX Offroad app that I originally used on a recent trip through Joshua Tree National Park. In this case, I downloaded offline maps of the entire Mojave Desert in low and medium resolution, then plugged in my target starting point where the Mojave Highway crosses I-95 south of Searchlight, Nevada. I connected OnX on my phone to the Cayenne’s aftermarket Sony head unit, which allowed me to run a larger map through CarPlay with a magnified north-south map on the phone. Together, this setup helped me avoid any wrong turns in the hot desert – stay tuned for a full review of the app ahead.
Playing with Cayenne settings
I love playing around with all of the Cayenne’s different drive settings. On the ride to the trailhead, I dropped the air suspension to Low and softened the shocks to Comfort. But once we got back into the dirt and rocks, I raised the ride height to High and switched the shocks between Comfort, Normal and Sport depending on the conditions. On higher-speed washboards, Comfort made for a smoother ride, but in rockier sections and whoops, Sport actually helped the SUV stay better balanced.
Climbing Paiute Ridge
The Paiute Ridge climb features a few sections that I might otherwise avoid without the Eurowise engine skid plate protecting the Cayenne’s underbelly. For the first half mile of steeper terrain, I flipped the transfer case between 4-High and 4-Low to experiment with traction before moving on to the harder stuff. On a hot day approaching 100 degrees with a bit of tailwind up the hill, the coolant temperature gauge started to climb towards 200 degrees Fahrenheit, even though the engine oil remained stable. Still, I decided to stay in 4-Low just to get the fluids flowing faster, while allowing the Aisin transmission to shift automatically.
Center differential locked in second
On the gnarliest segments of Paiute Ridge, I flipped the gear selector to manual to hold the transmission in second, then locked the center differential. Considering the twin-turbo V8’s 457 lb-ft of torque, first gear actually produced a little more slip than I wanted, while second kept the ride a little smoother, even at high revs. Choosing a cautious line, I climbed steadily up the rocky track, trying not to lift the throttle. Although my Cayenne left the factory without a rear locking differential or disconnecting stabilizer bars, the traction control can apply the brakes individually to prevent the single wheels from spinning in low-traction situations or when they are not touching the floor. And the Jeep behind me said I had multiple wheels about 18 inches in the air, multiple times.
The gripping brakes produced something odd feeling, however. For one thing, traction improves immediately. On the other, the thrill looks (and feels) a bit jarring. Plus, braking slows the 5,200-pound SUV and makes it all the more important to avoid lifting the throttle to avoid unintended stops. My own seat dyno suggested that the Montero with a true locking rear differential probably got through the tougher sections a little smoother, though the Cayenne still climbed Paiute Ridge without breaking a sweat. Maybe my own skills have increased with additional experience since my last visit to Paiute Ridge – or maybe the Cayenne’s ability made the difference – either way, I reached the top completely impressed. And I could risk that I could have finished the track without even using the low four-point differential or the locking center differential at all.
Bounce off the kick plate
I only felt a few impacts to the Eurowise skid plate, none of them significant enough to leave a noticeable mark or dent (at least, which I noticed without climbing under it or riding the Cayenne on an elevator). But I felt much more confident knowing that a thick hunk of steel was protecting that Porsche powertrain rather than the flimsy factory underbody pans, even as stray brush and rocks appeared on the higher-speed portions. of the day and sounded like a drum.
Next time even lower PSI
On the Cayenne’s next trip, I plan to air more at 20 PSI and hope to experience the full potential of the Toyo Open Country A/T III tires. Compared to the LT-metric Coopers, the Toyos felt a bit smoother at the same 38 PSI, and they tended to slip less despite the Cayenne’s prodigious low-end torque. But those impressions seem consistent with the P-metric tires that are 265 millimeters wide compared to the Montero’s 235. I still need more experience to stream the Coopers too.
Two enigmas of Cayenne
Two Cayenne enigmas arose during the trip. The former sparked my fears that complaints online that Porsche’s very compact engine compartment could lead to overheating. But on this second trip where the coolant rose in temperature with a tailwind, I came to the conclusion that the coolant simply heats up to 200 degrees as seen above to match the engine oil, without continuing any higher. I kept an eye on the gauge throughout the day and whenever we turned enough to create a side or head wind, the problem stopped completely. I guess if the coolant goes above 200 or the engine oil also starts to go up, then I must start to worry.
The other issue concerns ventilation in a vehicle equipped with a tire pressure monitoring system. The Cayenne’s TPMS actually works more reliably than any other I’ve experienced so far, but even with the slightly airy Toyos the dash showed the warnings visible overhead all day, which prevented me from checking the rest of the car’s computer readings. With no cell reception on Mojave Road, which makes OnX Offroad’s offline maps especially useful, I never found a way to clear these codes while streaming (and still haven’t do).
Relief broadcast for the return home
Throughout 45 miles of off-roading in the Mojave Desert, from the technical climb of Paiute Ridge to the smooth, high-speed sandy roads, the Cayenne performed about as well as I had hoped last October. Next, I plan to add some more pieces of Eurowise armor and then start working on building the cabin for a sleeping platform. In the meantime, after streaming the Toyos, the Cayenne showed off those impressive on-road abilities as it sailed me home effortlessly down the hot highway at 80 miles per hour with the air conditioning blasting.
Sources: coopertire.com, onxmaps.com, eurowise.com and toyotires.com.
Porsche Cayenne project: replacement of the main 12-volt battery