$63,700 buys you the Cayenne S; $62,725 nets the Infiniti FX50S. That FX price includes a $3k Sport package which I would call essential, since it means you get a more lithe, adaptive suspension, called Continuous Damping Control (CDC), and paddle shifters, among other goodies. That said, even with CDC, in both Sport and Auto modes, the FX defaults to a fairly rigid ride. This proves plenty engaging for the driver, but some passengers may grumble, especially if that driver decides to let the FX run hard.
The Porsche is more of a pussycat, though if you want it to show its fangs, buy it with Porsche Dynamic Chassis Control (PDCC), $3,510 and optional Porsche Active Stability Management (PASM; $3,980; price includes the required air suspension). The two Porsche systems do more than Infiniti’s CDC, since PDCC resists bending forces via hydraulically-assisted anti-roll bars on both the front and rear axles, while PASM, with Comfort, Normal and Sport modes, controls the stiffness of the dampers. Compared to the Infiniti’s adaptive shocks, PASM and PDCC allow the Porsche’s suspension to roll, rather than crash over potholes, but, when you want the Cayenne to handle in more Porschelike fashion, you can switch the dampers to their stiffest setting and the Porsche happily corners like a sports car (albeit, a fairly tall one).
A Little Greener
Porsche says its customers are increasingly asking for a greener product, a significant enough portion of the customer base in fact to prompt Porsche to make a hybrid S version http://www.thecarconnection.com/review/1047916_2011-porsche-cayenne Cayenne (for about $4k more than the S), as well as a hybrid version of the Panamera.
Even if you don’t want your muscle-crossover to be a hybrid, you can have one that’s at least middling on fuel economy: The Porsche Cayenne S gets 16 city / 22 highway, while the Infiniti turns in a poorer 14 city/ 20 highway.
One way to milk better mileage out of your Porsche is by using the start/stop function (that automatically shuts down the motor whenever the car sits idle at stoplights, etc., then restarts the engine once you’re ready to motor away). This is precisely the same function you’ll find in hybrids like the Civic and Prius, but here you get it in a non-hybrid that’s capable of outlapping anything that runs on electricity (this side of a Tesla).
In the Porsche the start/stop math wasn’t part of the EPA’s data for tabulating the Cayenne’s fuel economy. The reason is that the default is for start/stop to be in the “off” position. That said, the Cayenne S will save gas if you switch the setting to “on,” especially if your daily commute features lots of stop-and-go traffic.