Four years after its introduction, the Porsche Cayenne has become part of the automotive landscape. The car-buying public has demonstrated its appreciation of the Porsche brand beyond the company's familiar sports cars by purchasing them in numbers far beyond expectation.

The five-passenger SUV is technically slick and remarkably fast, as Porsches are supposed to be, with on-road handling that belies (though does not defy) its mass. The Cayenne also delivers what most SUV buyers demand: more cargo space than the typical sedan, more than enough capability for off-highway use and impressive towing capacity. For style, pure performance and a balance of sport-utility virtues, the Porsche Cayenne is tough to beat.

Porsche didn't sit still after the Cayenne's launch in 2003, adding a V6 drivetrain that opened the model to a larger group of buyers and more useful standard equipment and option packages. For 2006, in synch with its philosophy of adding even more power during a model's life cycle, Porsche offers the 510-horsepower Cayenne Turbo S, which takes the concept of a SUV muscle car to a highly rewarding extreme.

New features for 2006 include a new ignition key with separate lock and unlock buttons; new front airbag technology; an electronic logbook; an update to the Porsche Communication Management system that allows it to play MP3-encoded CDs; and a cellphone module that hooks into PCM. Optional equipment includes Offroad Navigation that lets drivers trace their way back to a starting point, even when the area doesn't appear on the nav's system's internal map. Wider rear 20-inch SportTechno wheels, an independent interior pre-heating and pre-ventilation system, new Dark Olive Metallic exterior paint, a new Sand Beige leather-wrapped steering wheel and seats with the Porsche crest embossed on the headrests are among other new options.

Like many Porsches, the Porsche of SUVs can be very expensive. An abundance of options means a fully loaded Cayenne Turbo S cracks the $125,000 barrier, and even the V6's fully equipped price reaches far beyond its $42,200 base price. Yet whichever powertrain sits beneath the bodywork, the Cayenne will be truly appreciated by those SUV buyers with exacting demands or unshakable brand loyalty.