Imagine, for a moment, that the Porsche engineering team has dropped 4,177 individually wrapped Twinkies on the lab floor. The yellow cream-filled sponge cakes are scattered shin-deep across the smooth ceramic tiles and kicked into the corners by technicians wearing white lab coats as more hit the floor. Individually, the cakes aren't very heavy. However, add 4,177 of the treats together and they weigh nearly 400 pounds.

Those thousands of Twinkies represent the average weight removed by Porsche on its all-new 2011 Cayenne. Thanks to a massive diet, the automaker's SUV emerges as a toned athlete – and we just spent two days flogging it on the track and off-road course at Barber Motorsports Park in Alabama. What's under its fresh new skin, and where did all that weight go? How does the Cayenne perform on the track? Just as importantly, has it lost its off-road capabilities?

Whether we liked it or not, Porsche's first sport utility vehicle debuted for the 2003 model year. A marked departure from the automaker's countless sports cars before it, the original Cayenne was a five-passenger sport utility vehicle that boasted both on- and off-road prowess and a choice between six- and eight-cylinder front-mounted, water-cooled powerplants. It was unlike anything that had ever worn a Porsche badge. If its design and primary mission weren't enough to petrify stubborn loyalists, the fact that it shared platforms and many of its components with the Volkswagen Touareg (and Audi Q7) was sure to have them choking on their salted pretzels.

Regardless, the 2.5-ton Cayenne flew out of showrooms faster than the venerable 911 – it soon became the automaker's best-selling vehicle. In truth, it is argued in many circles that the sports car company was saved by its SUV.

Eight years later, Porsche is rolling out the all-new 2011 Cayenne – arguably one of the company's most important debuts ever – especially if one considers sheer sales volume and potential profits. Like its predecessor, the new Cayenne shares its platform and components with its Volkswagen siblings, but Porsche has taken this model much more seriously. While the first-generation Cayenne was very competent, it was burdened by a heavy four-wheel-drive system and an appearance that never really looked completely cohesive.

With its engineers fresh out of SUV-rehab, the new Porsche model emerges with a purpose. The engaging new sheetmetal (all-steel fully-galvanized body panels) wrapped around the unibody platform speaks Porsche – from the raised fenders sitting higher than the hood to the instantly recognizable ovoid headlights. The designers blacked-out the B-pillars on the new model, and lowered the waistline, so it no longer looks like it's wearing its pants too high. The rear lights now wrap onto the liftgate, and the exhaust has been more cleanly integrated. While the overall package appears much sleeker, the drag coefficient has actually increased a tenth to .36 – styling took precedence. Vielen dank, Porsche!

Influenced heavily by the Panamera sedan – and moved upscale in appointment as a result – the Cayenne's cabin is greatly improved. The five-ring main instrument cluster is cleaner as it now features the familiar multi-function flat-screen display to the right of the tachometer. Dash vents have been lowered to flank the large navigation screen, while the center console picks up the HVAC controls. The buttons are overwhelming at first (when you get done with those, there are a dozen more overhead), but familiarization helps.

Porsche will offer four Cayenne models in North America in 2010. The first to arrive in just a couple months will be the eight-cylinder Cayenne S and the flagship Cayenne Turbo. The Cayenne S Hybrid and Cayenne V6 won't arrive until later in the year. As of now, there are no plans to offer the Cayenne Diesel on our shores.

Like the outgoing model, the 2011 Cayenne features fully independent double-wishbone suspension up front, and an independent multi-link design in the rear. Ground clearance, for the standard steel springs, is 8.7 inches. The Turbo model is also fitted with a self-leveling air suspension that adds variable ride height.

The front brakes are Porsche's six-piston aluminum "monobloc" calipers over 14.15-inch iron rotors on the S and S Hybrid models. The Turbo we spent most of our time driving wears similar six-pot calipers with larger 15.35-inch two-piece rotors – the rear rotors on all models are only slightly smaller in diameter, although clamped with four-piston aluminum calipers. As is the case with the rest of the automaker's lineup, Porsche's formidable "PCCB" carbon ceramic brakes (above) are optional. The standard wheel package includes 18-inch alloys wrapped in 255/55R18 tires on all four corners (all are "square" setups – none staggered). The Turbo is shod with 19-inch alloys wearing 265/50R19 tires (the one we drove on the track was fitted with optional 21-inch wheels wearing 295/35R21 tires).

The 2011 Cayenne S is fitted with a 4.8-liter V8, the same direct-injected 32-valve unit as last year's model, but minor tweaks have improved the engine's power slightly so it's now rated at 400 horsepower and 369 lb-ft of torque. The 2010 Cayenne Turbo bolts twin turbochargers to that direct-injected 4.8-liter V8 to produce 500 horsepower and 516 lb-ft of torque. Both powerplants share a new slick-shifting eight-speed "Tiptronic" automatic transmission with sliding shift levers on the steering wheel spokes.

While all of this sounds rather enticing on paper, the assemblage of German SUVs currently sold in North America includes not only the Porsche Cayenne, but the BMW X5 and Mercedes-Benz ML-Class – heavy hitters. Masterfully blending luxury, sport and utility, each of the fierce competitors is brimming with technology and innovation, not to mention volumes of excess poundage. Realizing that weight is the Achilles heel in this segment, the team at Porsche decided to get up off the sofa and do something about the problem.

Porsche's engineering team didn't just accept minor liposuction, they axed the fat off. The weight was shed from the body structure and wheels (lots more aluminum), but most of it was lifted when the Cayenne received a new electronically-controlled all-wheel drive system. All told, Porsche shaved roughly 400 pounds off the Cayenne's curb weight (yes, the weight loss works out to 4,177 Twinkies). On the scale, the new Cayenne S weighs 4,553 pounds while the Cayenne Turbo is 4,784 pounds. For comparison, the BMW X5 xDrive48i spins the dial to 5,335 pounds and the flagship X5 M simply flattens the gauge at 5,368 pounds. The Mercedes-Benz ML550 is 4,883 pounds, while the ML63 AMG weighs in at 5,093 pounds.

Low mass translates to better performance. Porsche says the 2011 Cayenne S model needs just 5.6 seconds to hit 60 mph (top speed is 160 mph) while the Turbo rockets to 60 mph in a conservative 4.4 seconds (top speed: 172 mph). Fuel economy numbers have not been released, but the automaker says we can expect double-digit percentage improvements.

As previously mentioned, our introduction to the all-new Porsche Cayenne was, interestingly enough, at the racetrack. This is no ordinary circuit – Barber Motorsports Park is a huge racing facility just outside Birmingham, Alabama. Opened in 2003, it features a beautifully manicured 16-turn, 2.3-mile road course that shames our West Coast facilities (if the Four Seasons hotel chain inexplicably dove into auto racing, this would be its inaugural facility). In addition to the very visible main circuit, hidden within the surrounding woods are countless off-road courses on the 740-acre property, which provided plenty of mud, ruts, hills and water obstacles. And yes, it's home to the Porsche Sport Driving School.

We've driven the Mercedes-Benz ML63 AMG and BMW X5 M (and X6 M) on the track more than once. Although all were plenty fast, the excitement level of driving 2.5-ton SUVs, even those "race-prepared" models, around a road circuit is akin to shooting glass bottles with a Nerf gun. It simply doesn't get our adrenalin flowing.

Expecting the same (so much for our optimism), we settled into the passenger seat of a normally-aspirated Cayenne S for an orientation lap with David Donohue, the famed 24 Hours of Daytona winner (currently driving a Daytona Prototype for Brumos Porsche). With bottled water in his right hand, Donohue guides the SUV around the corners at a brisk pace, yet he displays a casualness more commonly associated with driving to Sunday services.

Minutes later, we are strapped into the bolstered front left seat of the Cayenne. There is plenty of elbow and headroom in the cabin (even for the helmeted), and our view outside to the circuit is excellent (the exterior mirrors have been moved to the door, and there is now a small window at the base of the A-pillar to improve visibility). Our left hand turns the key and the V8 awakens with a throaty growl.

Maneuvering through the corners, we expect body roll, squealing tires and understeer, but the Cayenne fails to deliver the bad news. Instead, it seems to land on its feet with the competence of a luxury sport sedan (it felt like we were driving a BMW 5 Series). Flat in the corners, the center of gravity feels two feet lower (it isn't) as we smoothly flow around the track. This is crazy; the Cayenne has forgotten that it is a sport utility vehicle.

The Cayenne Turbo takes it up several notches thanks to its twin-turbo V8 (you cannot mock 516 lb-ft of torque), adaptive air suspension and Porsche Torque Vectoring (PTV) which helps set the chassis up in the turns (further reducing understeer). Fitted with the automaker's PCCBs (the ceramic brakes easily pull us down from triple-digit speeds), the only weak link seemed to be the contact patch after several hot laps (we can neither confirm nor deny rumors that the Cayenne Turbo is quicker around a road circuit than a standard Carrera... until the tires get overheated). We are seriously enjoying this.

Just to ensure we aren't completely inebriated with Porsche's 2011 Kool-Aid, we grab the keys to one of the school's 2010 Cayenne Turbo models for a back-to-back comparison. On the circuit, the current-gen Cayenne is pretty quick, but its steering feels loose and it understeers shamefully when really pushed. It's markedly evident that everything, from seats and steering wheel to suspension and chassis tuning, has been improved.

To demonstrate the new electronically-controlled all-wheel drive system is every bit as capable as its predecessor, we took a Cayenne Turbo (wearing standard 19-inch wheels) into the woods surrounding the track. While you probably won't see a Cayenne bopping over rocks at Moab, it is fully capable of doing so (Porsche notes that first gear on the new eight-speed automatic is low enough to pass for a low-range "crawl gear"). Even with standard all-season tires, no amount of muck could stop us. We climbed hills, dropped down paths (easy with a trick new hill descent system) and forged streams so deep that water flowed over the top of the hood – no joke. Even when the terrain was too much for the available suspension travel, the electronics took note and shut down power to the airborne wheel. If you get stuck in a new Cayenne, your common sense has failed you, not the other way 'round.

We left the paddock of the track and headed out on the highway to check out the Cayenne's on-road etiquette. While it isn't nearly as fun at 65 mph, the lower velocities gave us some time to play with the navigation system and other controls. Porsche's logic is that switches are easier and faster to use than fumbling with a joystick-type controller. We agree, once you learn where the buttons are (did we mention that there are a lot of buttons?). Our other nitpick had to do with cabin noise as our ears picked up a bit more road thrum than we recall from its predecessor (remember, there is a lot of weight tied up in sound absorbing materials).

The V8-powered Cayenne S model will set you back $63,700 when it arrives this summer, while the range-topping Cayenne Turbo starts at $104,800 (none of the prices include destination charges). Of course, these are all base prices. Porsche will merrily dangle a long list of attractive options to successfully extract another 20+ percent out of you before you leave the dealership floor.

Back in 2002 when the first Cayenne hit the pavement, many of us around here aligned with the naysayers and grumblers, those who felt the traditional sports car manufacturer had betrayed its loyal following by introducing a 5,000-pound sport utility vehicle. Truth is, even after the automaker bolted on a couple of turbochargers to mask most of the weight, the original SUV still had a certain elephantine feel about it.

Today, fresh out of the fat farm with a refined set of running gear and some sexy new clothes, the automaker's hot pepper finally dances like a sport sedan. While it's no twinkle-toed Fred Astaire – and it never will be – the all-new 2011 Porsche Cayenne is finally good enough to turn those petrified cynics into believers.

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