Jerry Barstow, Contributor
Just like every other carmaker, Porsche must deal with a future determined as much by politics as by the marketplace. Sure, Zuffenhausen's most famous enterprise will continue making blindingly fast sports cars into the foreseeable future, but it's also going to have to build (gaack), diesels and hybrids.
And so we introduce you to the 2011 Porsche Cayenne S Hybrid. Welcome to the latest battle over Porsche's soul.
What the Markets Expect With the sort of cold calculation one expects of Porsche since Wendelin Wiedeking took over as CEO in 1993, the company determined some time ago that it would have to develop both diesel and hybrid technologies to remain competitive in the large-SUV segment. Diesel, because that's what customers and the regulatory environment in Europe expect. And a hybrid system because that's what the customers and regulatory environment in North America seem to want.
Fortunately, thanks to Porsche's ever-tightening hammerlock on the VW Group now that it has financial control over its much larger partner, the company did not have to pursue these expensive technologies on its own.
So the gas-electric hybrid system that will work its way into the 2011 Porsche Cayenne S Hybrid will also likely be used in its "Colorado" platform mates, the Audi Q7 and Volkswagen Touareg, and might eventually wind up in the upcoming Porsche Panamera sedan, too. Fortunately it's a neat system with some interesting innovations, even in the preproduction form that we experienced here in the Cayenne Hybrid.
One or the Other For the most part, Porsche's approach to the hybrid is a straightforward parallel system, though it's more like that in the new Honda Insight than the more sophisticated technology of the Ford Fusion Hybrid and Toyota Prius. The Porsche system differs from Honda's IMA arrangement in that a clutch between the engine and the electric motor allows the V6's crankshaft to be stopped. (The Honda system instead reduces pumping losses by using a VTEC motor to shut the valves while the crankshaft continues to turn.) In any case, stuck between the Porsche's supercharged, 333-horsepower, direct-injection 3.0-liter V6 engine and the eight-speed automatic transmission is a three-phase synchronous electric motor rated at 38 kilowatts (52 hp).
When both the electric and internal combustion engines are working together, there's up to 374 hp available for acceleration. Under deceleration or braking, the electric motor acts as an alternator and feeds juice to charge the 240-cell nickel-metal hydride battery array that's nestled behind the rear axle where the spare tire would be stowed in a conventional Cayenne.
Sailing Like other hybrids, the 2011 Porsche Cayenne S Hybrid shuts down its engine at a stop to save fuel. The electric motor's purpose is to start up the engine again. But as people expect from hybrids these days, under very light throttle the Cayenne Hybrid will glide silently forward under pure electric propulsion at speeds up to about 30 mph. Unlike other hybrids, however, the Porsche turns off its supercharged V6 at higher speeds and, using a special clutch, disconnects the V6 from the drivetrain altogether. This allows the SUV to "sail" along, unfettered by the usual engine braking. To any of us who grew up riding ten-speed bicycles, what Porsche calls "sailing" is better described as freewheeling. What's really going on here is that the Porsche Cayenne uses a bigger electric motor than the Honda Insight, so this freewheeling strategy allows the motor's regenerative function to soak up as much juice as it can to recharge the batteries, providing all of the necessary engine braking in the process.
In its current form as a prototype, the only obvious difference between the regular Cayenne and the Cayenne S Hybrid (discounting all the "Hybrid" lettering) is the slightly raised rear cargo floor over the battery pack — it's about an inch taller than the cover in a non-hybrid Cayenne. Porsche swears that by the time the Cayenne S Hybrid enters production, the height of the cargo floor will once again be the same as that of the other Cayenne models. And in lieu of a spare tire, Porsche will give you a can of tire repair goop with each hybrid.
There aren't any final mpg numbers yet (EPA testing is still a ways off), but Porsche is claiming that fuel economy will improve to the level delivered by a four-cylinder engine, while performance will be slightly better than the Cayenne S with its V8. The CO2 emissions (carefully regulated in European markets) will be less than 210 grams per kilometer — about 20 percent better than what would be considered normal for a vehicle of the Cayenne's weight and power.
Of course, for a traditional Porsche buyer, greenhouse gas emissions don't matter anywhere near as much as hothouse performance.
Drives Like a Hybrid? Or a Porsche? Mechanically there's a lot going on with the 2011 Porsche Cayenne S Hybrid. After all, this is not only Porsche's first hybrid but also the first Porsche equipped with a mechanical supercharger, first with an eight-speed transmission and first with electric power steering. It isn't simply a Cayenne with a battery pack.
Fortunately, Porsche hasn't buried the drivetrain so deeply in the Cayenne S Hybrid that you can't hear and feel what's going on. Even under electric power, there's still a perceptible connection between the driver and the vehicle. It's not a direct connection such as what exists in, say, a Boxster, but the electric motor audibly whines and there's some road feel through the steering.
Mash the throttle and the slight whine of the Roots-type blower atop the Audi-built V6 becomes apparent. The Aisin-made gearbox shifts innocuously right up through all eight gears. Although the hybrid only weighs 140 pounds more than a conventional Cayenne, the suspension is so stiff that you feel the road a bit more than you'd want. The sailing feature can be disconcerting at first, but acclimation comes quickly and eventually you start looking for long downward slopes to push the mpg-enhancing benefit of freewheeling out to its maximum advantage.
A New Kind of Porsche Performance So the Cayenne Hybrid is not an isolation chamber like the Lexus RX 450h. But it's less involving than other Porsches, not to mention other Cayennes, too. There's just no way to keep the driver truly involved when a powerful computer like this Porsche's "Hybrid Manager" brain is responding to 20,000 data inputs. Considering the Cayenne S Hybrid's excellent acceleration and high-speed stability, this is an impressive hybrid, even as a hybrid. But it's still a hybrid, with most of the compromises in its visceral impact that we've come to expect from previous hybrids.
Of course, for some buyers the 2011 Porsche Cayenne S Hybrid will still be plenty of Porsche. But will they be willing to pay a $6,000 or $7,000 premium for it? One gets the feeling that even Porsche doesn't yet know the answer to that. We'll all find out some time in late 2010 when the first buyers start writing checks for more than $70,000.
Nevertheless, political realities being what they are, Porsche knows it has to build this hybrid, just like it had to build an SUV in order to be able to keep making sports cars.
Edmunds attended a manufacturer-sponsored event, to which selected members of the press were invited, to facilitate this report.
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