words: Eddie Alterman

What we have here are two vehicles not particularly high on the Sierra Club's Christmas-card list. The Infiniti FX and the Porsche Cayenne, both hatched in 2003, are the original hardcore performance utes — no third rows of seats here, no hybrid drivetrains (yet), no cute little puffs of water-vapor tailpipe emissions through which cartoon bunnies may frolic. Their social acceptability has fallen as gas prices have risen, and they're probably in danger of becoming an agenda item on the next round of Kyoto protocols.

But here's the thing: As much as we're down on the profligate consumption of oil, these sub-20-mpg'ers are among the only big-n-tall vehicles we really want to drive hard, two of the few that don't handle like cardboard boxes. The FX50 ($55,000, est.) and the Cayenne S ($57,900) are sports cars with a bad case of gigantism, under whose elephantine husks pulse the reflexes of mice. And though painted with the same brush by SUV-haters, these two vehicles present two distinct takes on the performance bruiser.

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The Cayenne is, by our definition, a crossover: It employs unit-body construction and a very carlike suspension concept underneath. But with its amazing and seldom-seen off-road ability (its approach and departure angles, for example, are as high as 32/28 degrees), it is as dirtily capable as many a body-on-frame sport-utility vehicle. Also, it can tow 7716 pounds. With a healthy dose of German literalism, the Cayenne clings to the now quaint notion that something that uses as much sheetmetal as an off-roader ought to be able to perform like one.

The original Infiniti FX blazed a still-smoking trail for soft-roaders. It was the first crossover to claim the far end of the on-road performance spectrum, prizing handling, braking, and speed above all else. This new FX50 is still a sport-sedan writ large, but now it's also a technological tour-de-force. For all the Cayenne's chassis systems — PASM, PSM, PDCC — Infiniti has easily outdone it on the electronics-abbreviation front. This is less a sport-crossover than a cunning collection of solenoids, all employed to keep the FX fast, safe, and stable.

With this new FX coming soon and a heavily revised Cayenne here for the 2008 model year, we felt it was time to get these two together again. True, a more conventional test might have been to pit the FX against the new BMW X6 "coupe-ute," but to do that would be to miss some larger questions about this segment, such as: Did Porsche have the formula right all along? Can on-road agility and off-road ability be maximized in the same vehicle? Or would Porsche have been better off ditching the AWD mechanicals in admission that it's ridiculous to go mudding in one of these things in the first place? And: Can a vehicle of the FX's size and weight perform well enough on road to justify its lack of a transfer case? Or is the FX its own kind of ridiculous, trying to be a focused sporting machine in a crossover's body?

Interior/Exterior
But before we get there, let's poke around a little. The FX50 is trim and elegant inside. It has a small, multifunction steering wheel; heavily bolstered and diagonally stitched sport seats; and the cocooning greenhouse and driving position of a sports car. It offers good leg, hip, and shoulder room, but with its high dash top and compact controls (e.g., stubby shift knob, lots of small buttons) the mood is business-like and driver-oriented. Options abound: You can load in a 9.3-gigabyte, hard-drive-equipped entertainment system; the new Automatic Driving Position system that maintains the relative placement of your steering wheel and side-view mirrors whenever you adjust the seat; a filtration unit that acts as a sort of in-car Ionic Breeze, ridding the interior of mold and fungi; and the miraculous Around View system, whose four cameras depict the plan view of the FX in real time and space, and is about the coolest thing ever. It's also necessary, as the interior C- and D-pillars nearly merge into one.

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The FX exterior, though, is what people will point at. Its slim greenhouse and powerful stance are almost concept-carlike in their execution. For the redesign, the FX gets a wider front track and a 1.4-inch longer wheelbase, and, sitting on 21-inch wheels, its suggestion of power is unmistakable. There are even air extractors behind the front wheel wells — perhaps a bit of overplayed car jewelry nowadays, but they are functional here. They pull air from the engine compartment out through the sides, reducing front-end lift by 5 percent to calm the car at high speed.

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Not much has changed inside the Cayenne for 2008. Our car had the familiar Stone Grey/Steel Grey leather package (free of charge), which looks vaguely pachydermal. The Porsche's taller, more traditional glass keeps the cabin airy; the driving position is upright, giving it good sight lines. Interior tweaks for 2008 include a Sport mode button, a power liftgate, and a cargo-management system in the bed area. Somewhat shockingly, the FX has more luggage capacity than the Cayenne with the rear seats up (23 vs. 19 cu ft), and only loses half a cubic foot to the Porsche with the rear seats folded. (62.0 vs. 62.5). True, the FX is about two inches longer, but the Cayenne forfeits some cargo volume to the aggressive rake of its rear glass and to a load floor that is relatively high — understandable in the presence of a long-travel suspension and two locking diffs underneath.

The Cayenne's exterior adjustments aren't as dramatic as the FX's, but they serve to make the Cayenne both more attractive and more aerodynamic. The whole front has been canted back, the headlights and side mirrors are new, and the wheel openings have been re-sculpted. This brings the drag coefficient down from as high as 0.39 to 0.35 for all models.

Chassis
High-speed stability is exemplary in both vehicles, but these two weren't built for cruise control. When the Cayenne came out, Porsche engineers argued that the optimal suspension configuration for on-road handling and off-road grip was double wishbones all around, and it appears that Infiniti agrees, as it ditched the FX's front struts for 2008 (it still uses a multilink rear). The FX's suspension is closer than ever to that of the Nissan corporate FM layout used by the 350Z, the G35/37, and the M35/45.

Our Cayenne's carryover four-wheel-drive system and chassis had the air-spring package with Porsche Active Stability Management and Porsche Dynamic Chassis Control (which all but eliminates body roll), but it is summarily outdone in the driving-aid department by the FX. Like the Porsche, the Infiniti has defeatable stability control, as well as Continuous Damping Control (electronically modulated shocks). But it also boasts Intelligent Braking Assist, which will squeeze the rotors preemptively when it senses an impending crash; Distance Control Assist, which is a sort of smart cruise control; and the Lane Departure Warning system that beeps annoyingly when you weave in and out of your lane while juggling your iPhone, BK Steakhouse Burger, and Starbucks back-to-basics coffee. Luckily all this stuff can be shut off, so as not to interfere with the enthusiast driver's agenda.

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Speaking of which, the FX brings the excellent ATTESA ET-S all-wheel-drive system that starts at a 50:50 split and can transfer 100 percent of the torque rearward. And, for the first time ever on an SUV, Infiniti has installed a rear-steer function whose electric motors can turn the rear wheels up to one degree for sharper cornering and enhanced high-speed stability.

Dynamically, the two chassis are fairly evenly matched. The Porsche wins on initial damping quality, erasing road imperfections like a grader. But in terms of wheel-impact harshness, the Infiniti is no longer as kidney pureeing as the FX45 used to be. Also, its secondary ride is bit better than the Porsche's, inflicting none of the head-toss that occasionally crops up in the Cayenne. Both can perform lurid acts of power oversteer at will, but will drift neutrally if properly set up. With its quicker steering rack and rear-steer function, the FX feels more nimble and turns in faster than the Cayenne. But nothing can touch the linearity and communication of the Porsche's steering feel. It's frankly amazing that Porsche has come so close here to the steering character of the 911 and Cayman, cars that don't have to deal with that massive lump of an engine up front.

Performance
Porsche revised said engine for 2008 with direct injection and VarioCam variable valve control. The naturally aspirated 4.8-liter V-8 makes 385 hp at 6200 rpm and 369 lb-ft of torque at 3500 rpm, and passes through a six-speed Tiptronic S gearbox. The Infiniti's VVEL 5.0-liter V-8 (bored and stroked from the FX45's 320-hp 4.5-liter) makes five more horsepower than the Cayenne S and exactly the same amount of torque, albeit at higher revs. It cuts the torque more finely, though, thanks to the FX's seven-speed manumatic transmission. Both vehicles' final-drive ratios hover around the 3.5:1 mark.

With powertrains so similar, it seemed odd that, in our testing, we couldn't get the Cayenne S to within a second of the Infiniti. Here's how they stacked up:

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Weight, obviously, is the culprit. The Cayenne S hides almost 400 extra pounds under its skirt, tipping in at 4950 versus the FX50's 4575. Although the Porsche posted respectable numbers, the Infiniti simply ran away from it through the midrange. In testing, the FX's power delivery was far more linear than the Cayenne's, and its manual shifts were cleaner and faster. And for all the Porsche's legendary braking prowess — the pedal feel is amazingly natural, allowing you to easily grab one consistent pressure all the way to a full stop — the Infiniti is within range, both in terms of feel and stopping distance. Looks like someone needs a little TrimSpa.

Conclusion
What these two pioneers of the performance-crossover genre reveal most strongly are their countries of origin. The Infiniti couldn't be more Japanese, using a couple of supercomputers' worth of processors to do its thing. The Cayenne, being German, clings to its mechanicals, and as a result has a far wider range of capability than the FX — wider, in fact, than anything else on the road. Still the questions persist: Why has Porsche made such a fast crossover with all that off-road dexterity? And why has Infiniti made an off-roader that really can't go off-road?

After driving both hard for a week, we think we have the answers: In the case of the Porsche, the Cayenne S is of a piece with the marque's sports-car philosophy. Porsche disdains single-purpose vehicles; it tries to make cars that are good at everything. Ferry Porsche famously said the 911 is the only sports car that can go from the Monte Carlo Rally to the opera, and the Cayenne is capable of its own kind of miraculous transformations: It will stick to the side of a 45-degree boulder even as it out-laps sport sedans on the Nordschleife.

The FX, on the other hand, is a carefully examined reflection of the crossover buyer's realities. It concedes that, in this segment, fashion and speed are easily as important as off-road functionality. Either Infiniti understands the market better or Porsche is unwilling to compromise its ethos, or both. Whatever the case, there's no denying that the FX is a stunningly fast and entertaining machine. But the Cayenne's not that far behind, considering that it can cling like a spider to a rock face. Also, it must be said, you can get a Cayenne that goes faster than the FX50, but it will cost you twice the money.

So for most buyers, it's a no brainer. Why get all that mechanical all-wheel-drive gear you'll never need, as it only impedes the Cayenne's performance with additional mass? And yet, for another kind of sportsman, the gent who understands and embraces the nuttiness of these things in general, why, indeed, shouldn't his $60,000 crossover be able to navigate the Rubicon Trail and Road America? At this level, what matters is perceived performance, and the Porsche simply has more of it than anything else. If we were richer, or actually went off road, or towed two classic 2.7RSs, or had more people to impress, we'd choose the Cayenne. Until then (a day we hope comes soon), we'll take the FX.