Question: What is Porsche's best-selling model?

Could it be the iconic 911? Sorry. Perhaps the recently introduced Panamera sedan? Nope. Maybe the more affordable Boxster? Not even.

The answer is the Cayenne SUV.

Do you find anything odd about a two-ton SUV being the undisputed sales king of the German company known for making sports cars? While enthusiasts revel in the performance of the company's small sports cars and the brand's racing history, the fact is that Porsche is a business. It has employees that conceive of, design, build, and sell products.

From a business perspective, Porsche is just a manufacturer of widgets, and for a company to remain a going concern, said company must sell widgets at a profit. Increasing the number of widgets is also smiled upon by shareholders. This is why Porsche builds the Cayenne: It's good business.

Since its European introduction in 2002, the Cayenne has been Porsche's top sales performer, with more than 280,000 sold. According to insiders at Porsche, profits from the Cayenne helped fund the development of the most recent 911, Boxster, and Cayman models, as well as the Panamera. The SUV has been good for the company and ergo, good for enthusiasts who love the cars that make the company Porsche.

With the onset of the 2011 model year, the Cayenne SUV would have been nearly as old as Methuselah himself (in car years), so it was time for something new. Porsche delivered; the entire vehicle is redesigned and the changes are significant.

The 2011 Porsche Cayenne. Click on the above photo to see more pictures (Michael Harley, Autoblog)

Rolling out this summer and fall, there are four distinct models and we've driven all of them: The base Cayenne with 300 horsepower, the Cayenne Hybrid S with 380 hp, the non-hybrid Cayenne S with 400 hp, and the mighty Cayenne Turbo with 500 horses.

All New And Better For It

Outside and in, the 2011 is so much better than the popular outgoing model that Porsche could have stopped with a new exterior and a duly revised interior. But they didn't.

Under the new design, the new Cayenne is much more Porsche-like than the old. First, it's nearly 400 pounds lighter. This is significant and impacts the SUV's dynamic performance and fuel economy in a big way.

There are two distinct suspensions: One uses conventional steel springs while the other is an air suspension marketed as the Porsche Active Suspension Management. A $3,000 option, we much preferred the air-assisted ride as it provides an exceptionally smooth and stable ride plus suspension settings that ranged from luxury car downy to sporty stiff.

We marveled at the Auto-Stop function, not because we've never seen it before, but that this fuel-saving technology seemed out of character for a sports car company. This feature turns off the engine when the Cayenne is stopped in traffic and immediately re-starts as the driver lifts off the brake. Additionally, the audio and ventilation systems remain fully functional, as do all safety systems. This feature was necessary to meet new European Union C02 standards, so the Auto-Stop function is active unless the driver disables it. U.S.-bound Cayennes, however, don't have to meet the EU emissions standard, so the driver must activate the Auto Stop function when they feel like being frugal.

The 2011 Porsche Cayenne. Click on the above photo to see more pictures (Michael Harley, Autoblog)

Porsche's drive train project manager, Christian Heiselbetz, told us, "When we started the new Cayenne program several years ago, Americans weren't so concerned about fuel economy. We didn't think they'd value the feature, so we made it necessary for the driver to engage it. We think that we will reverse this in the future."

The substantial diet and Auto-Stop function weren't the only things Porsche did to improve efficiency. Every Cayenne uses a new eight-speed automatic transmission. Having more gears saves fuel while delivering improved acceleration.

All other Porsche models are available with the company's twin-clutch automated manual, the Porsche Doppelkupplung, PDK for short. The gearbox is known for its exceptionally quick shifting, and we asked why it wasn't fitted to the Cayenne. Heiselbetz explained, "The Cayenne is heaver than our other vehicles, plus it must have the ability to tow and drive off road. A torque converter (a component in the eight-speed conventional automatic transmission) is part of what makes those capabilities possible." The Cayenne is rated to tow 7,716 pounds, plus it has substantial off-road capabilities that are used by some drivers, especially those in the Middle East who dune surf.

The Best Excuse Yet For Buying A Hybrid

The performance of the 500-horsepower Cayenne Turbo didn't surprise anybody, but the on-track hustle of the most complex Cayenne ever did. When we got behind the wheel of the $67,700 Hybrid S, we felt as if we were sitting in the middle of the world's most harrowing compromise: A Porsche... that's also an SUV... and a hybrid. There must be a black hole for that sort of quandary.

The Hybrid S uses a combination of a supercharged 3.0-liter V-6 and electric motor to crank out a combined 380-hp at 5,500-6,500 rpm and 428 lb-ft at just 1,000 rpm. The gasoline engine is supplied by Audi (a sister company of Porsche) and makes 333 horsepower on its own. The electric motor produces 47 horsepower, but more importantly, it alone produces peak torque of 300 lb-ft off idle, with half as much still available at 2,250 rpm. For the technically inclined, engineers don't add the individual power numbers of the gas engine and electric motor together because their power peaks occur at different speeds, making a blended figure for the complete hybrid powertrain a more accurate measure.

The 2011 Porsche Cayenne. Click on the above photo to see more pictures (Michael Harley, Autoblog)

This power enables the hybrid to accelerate from 0-60 mph in just 6.1 seconds. This is only 0.6-seconds slower than the V8-powered Cayenne S. Conversely, the Hybrid S is 1.3-seconds faster to 60 mph than the base V6 Cayenne, but delivers significantly better fuel economy. Official estimates aren't available, but expect the Hybrid S to achieve in the low 20s city, with more than 23 mpg highway. When it comes time to brag about more than mpg, the Hybrid S has a top speed of 150 mph.

On the road, the Hybrid S drives like a sporty V8 SUV with one exception. Porsche engineered a "sailing" function into the hybrid powertrain. Unlike most hybrids that use heavy regenerative braking to re-capture the kinetic energy for battery charging, when a driver lifts off the Cayenne's throttle, the SUV figuratively "sails" because there is almost no powertrain drag.

To understand the concept, imagine driving 90 mph in a conventional SUV and putting an automatic transmission in Neutral. It's the same feeling, except in the Hybrid S, the SUV feels as if it might coast forever. By allowing the engine to shut down at speeds up to 97 mph, the hybrid system can save fuel even at highway speeds.

In around town driving, the Hybrid S can motor up to 40 mph on battery power alone in ideal conditions. Expect 15-25 mph under most normal operating conditions and less if it's exceptionally warm or cold out.

As for how it all works together, we expect most Hybrid S drivers will think it's cool. After all, they're not buying this Cayenne because they love pure Porsche performance.

"People who want to drive a Cayenne don't want to be blamed by their neighbors for killing the world with C02. It's a pure business decision. Customers want it,” said Porsche’s Dr. Michael Leiters.

Such thinking will secure that those who love the performance-focused 911, Boxster and Cayman will have new models in the pipeline. It's just business.