• Mar 10th 2009 at 11:58AM
  • 24
Porsche Cayenne S Hybrid - Click above for high-res gallery

While charging along at 85 mph with a particularly poker-faced Porsche engineer riding shotgun, traffic begins to cluster on the horizon. Not willing to risk our seven-figure prototype, I gently roll off the accelerator, at which point a funny thing happens: Without warning, the tachometer needle dies, unceremoniously plunging to zero RPM. The supercharged, 3.0-liter V6 ahead of us has gone stone dead, yet our Porsche Cayenne continues to waft along unruffled. We are coasting along on the Autobahn, with only a modest bit of wind noise and tire roar as our soundtrack.

Just as quickly as it began to appear, Stuttgart's traffic thins, and after gliding along for perhaps 15 or 20 seconds -- losing remarkably little velocity -- I ease back onto the throttle, at which point the rev counter jumps back to life just as quickly as it had extinguished, and the Cayenne sashays back up to 95 mph before I slot in amongst slower traffic in the right lane. Beyond the tachometer's telltale drop and jump, there is exactly no indication that the engine momentarily packed it up just seconds before. My copilot, Dr. Michael Leiters, project manager for Porsche's Cayenne Hybrid, allows himself a brief smile.

Far from indicating a mechanical defect, we've just witnessed what our Deutsche companion refers to as "segeln" -- sailing -- a fuel saving maneuver that Porsche says other automakers have written off as impossible at roadway speeds without jolting disruptions. Yet beyond the tach needle's machinations, there has been no drama whatsoever: no untoward thwack in the back, no expensive-sounding noises, no head toss, no coffee spilled, just seamlessly reintroduced acceleration. The gas pedal simply called upon the engine again and the electric motor restarted it in a flawless, 300-millisecond passing of the power baton. Remarkable stuff.

Follow the jump for more.

Our travel and lodging for this media event was provided by the manufacturer.

Porsche Comes Through In The Clutch

Unlike any other gas-electric system currently on the market, our Cayenne S Hybrid tester has an additional mechanical clutch that decouples the engine entirely, temporarily removing it from the driveline equation. Doing so means the V6 is not a source of parasitic drag, and the modestly-sized 52-hp electric motor can nudge the Cayenne gently along as it does its inertial thing unencumbered. What is "modestly-sized," exactly? Porsche says the complete hybrid module – including the electric motor and the additional clutch – is just 5.8-inches long.

The German automaker figures this electronically-orchestrated party trick will save them a couple of percentage points when it comes to fuel consumption, but we reckon that the gains could be substantially greater under the right conditions – a drive route incorporating long downhill grades, say. If one lives in a mountainous area like Denver, Colorado, it's theoretically possible to start the Cayenne's ball rolling, and then coast all the way down to the base of a slope – a run that can sometimes last for many miles – without using a drop of fuel and without resorting to tactics like shifting into neutral to avoid engine braking.

In fact, using the brakes to slow one's descent will store energy in the nickel-metal hydride battery pack thanks to regenerative braking technology, so theoretically the entire descent could result in a net-energy gain. If you're particularly delicate with the throttle, this sub-cargo-floor mounted battery pack should allow for slow-speed electric-only running for up to 1.2 miles, but in practice we found this harder to do than with other gas-electric systems we've experienced.

Porsche's so-called "Hybrid Manager" is no small achievement – this bit of hardware supervises all major systems (engine, electric motor, transmission, battery, etc.), and reacts by issuing any of 20,000 data instructions, as compared to a traditional ECU that requires only 6,000 commands. Porsche notes that the 'sailing' capability can be activated at speeds of up to 86 mph (far faster than that of other hybrid systems), making it a viable energy-saving partner for both city and highway duties.

Gearing Up

Unlike most hybrids, Porsche says the production hybrid Cayenne will eschew use of a continuously-variable transmission unit in favor of a more conventional eight-speed gearbox from Japanese supplier Aisin, albeit one with an electrically-driven oil pump. Why no CVT? Officials explain that while this Cayenne is a hybrid, it is first and foremost a Porsche, and CVTs generally fail to deliver the sort of driving enjoyment that a conventional Tiptronic can. Despite their many advancements over the past few years (including the institution of paddleshifters with artificially preset ratios to preserve the mental "shifting" experience), we agree wholeheartedly.

Our tester's powertrain suffers no "stretched rubberband" moments that are the hallmark of most CVTs, and it was all the better for it. Unusually, top speed is reached in sixth, with the seventh and eighth cogs reserved as fuel-savers. It's that top gear that allows the Cayenne to "sail" at 86 mph with the engine shut off and the electric motor coaxing it along. We inquired as to the viability of a dual-clutch transmission like the PDK, but were told that fitting one would be tremendously difficult, so for now, Tiptronic it is.

In nearly every other area of operation, our prototype parallel hybrid functions in an almost indistinguishable manner versus a traditional gasoline-powered Cayenne. The combustion engine has been borrowed from Audi, with a belt-driven Roots-type supercharger nestled between its directly injected cylinders. So equipped, the engine generates 333 hp and 324 pound-feet of torque. Unlike in other gas-only Audi applications, the air-conditioning compressor and electrohydraulic steering pump are powered by the battery pack. For its part, the electric motor adds up to 221 pound-feet of torque. Combined, Porsche figures the two power sources are good for 374 bhp and 405 lb-ft of torque at just 1,500 rpm.

As part of its energy-saving regimen, the hybrid will be the first Cayenne to utilize electrohydraulic power steering. Porsche says it consumes 93% less energy than its conventional hydraulic counterpart, and in our limited drive time, it managed to deliver good accuracy, although we wouldn't mind it if Porsche dialed in a skosh more weight at highway speeds.

By The Numbers

While final fuel economy testing has yet to be completed, Porsche expects the powertrain to deliver performance akin to that of the V8 Cayenne while sipping fuel like a four-cylinder. 0-62 mph checks in at a conservatively-estimated 6.8 seconds, and top speed is limited to 133 mph. Even towing capacity and off-road ability is said to be unchanged. What is different, however, is miles-per-gallon and C02 output -- the latter figure being of great importance to those living under the various Byzantine emissions-based tax structures that govern most European nations. Porsche's new hybrid drivetrain sips fuel to the tune of 8.9 liters of fuel per 100 kilometers (62 miles) traveled when measured on the New European Driving Cycle (around 26 mpg U.S.), equal to C02 emissions of less than 210 grams-per-kilometer. That's an improvement of more than 25% over the V6 Cayenne, and the production vehicle is expected to be ULEV II compliant when it comes to North America.

While other automakers have elected to play up their vehicle's hybrid credentials, it is likely that Porsche will choose a more restrained route when the Cayenne Hybrid reaches production. The massive hybrid decals that run along the bottom of the bodysides won't be a mandatory "feature" as they are on General Motors' GMT900 SUV hybrids, and Stuttgart has not yet determined how it will badge the vehicle. Inside, Porsche has also resisted going the "Greener Than Thou" route with lots of fancy fonts and gimmicky display graphics like wilting digital flower petals. No games. No "monkey cinema" as Dr. Leiters refers to it. Oh, there's a screen that can be summoned on the navigation system which details where energy is being routed and a small in-cluster indicator, but Porsche assumes that you'll ignore these after you get used to hybrid driving. In stereotypically Germanic fashion, this Cayenne is all business.

Why Not The Diesel?

Despite much purist hand-wringing upon its introduction, the Cayenne has been the linchpin in Porsche's product portfolio since going on sale in 2002, particularly in the States. And although officials aren't talking model-mix projections, this gas-electric model figures to be an especially important offering in hybrid-happy America. For the moment, Porsche says it has no plans to bring over its excellent new Cayenne diesel, a powertrain whose great slugs of torque and excellent highway fuel economy is perhaps better suited to typical U.S. driving patterns (hybrids are most effective when poking along in thick urban traffic, where slow-speed trundling from bottleneck-to-bottleneck can often be conducted purely on electric power, but fewer Americans live in and around major city centers compared to their European counterparts). Despite this, America's appetite for diesels is still dwarfed by that of Europe, and with inflated fuel prices (versus gasoline) and soot-spewing memories of diesels past, it is likely that Rudolph Diesel's combustion cocktail will remain second fiddle to hybrids for some time.

Pricing also figures to be something of a sticky wicket, as all of the requisite hybrid R&D and associated hardware figures to add something on the order of $15,000 per unit (Porsche will not disclose projected sales volumes). That's a premium far too great for customers to absorb – even with the possibility of tax breaks. In light of this cost barrier, we expect for the Cayenne hybrid to sticker for something well north of a conventional V8 S model, ($60,215), perhaps along the lines of $67-70k, albeit with additional standard equipment to soften the blow. Given that performance is similar to the V8 engine and that fuel economy and emissions are markedly superior, this figures to be a reasonable surcharge for affluent folks eager to play the "green card."

What's Missing?

Porsche says that their hybrid system is "only about 90% of the way there," although at first blush, it's already so polished that we struggle to think where a 10% improvement could come from. If we have any reservations with this setup, it's a sin by omission -– a lack of noise. The inherently quiet nature of a parallel hybrid ignores the important aural performance link that Porsche has worked hard to establish with its vehicles and with the Cayenne in particular. Remember the commercial with the new owner revving his Cayenne Turbo in his driveway? How about the more recent and altogether fabulous Cayenne GTS "bloodlines" spot? While the 3.0-liter V6 in the Cayenne Hybrid S is a very good engine, it isn't terribly special sounding, and at points it makes no noise at all. What's more, we suspect that the consternation surrounding the pedestrian safety risks associated with silent-running hybrids and electrics will only grow when more vehicles reach elevated speeds.

While we could go on about other key aspects of this Cayenne – the handling, ride and interior -- our drive was limited in time and scope, meaning that beyond concentrating on the hybrid powertrain, we didn't have much time to assess the total driving experience. Not that this is a real problem, as it's all likely to change appreciably the time the Cayenne Hybrid comes to market.

How's that? Although officials would say little that wasn't non-committal, we know that the next-generation Cayenne is well along in development, and it is poised for release sometime after the Panamera launches, likely in 2010 as a 2011 model. As Porsche is smart enough not to bother with the expense of fitting and certifying a brand-new drivetrain for a vehicle that's about to go off the market, we can reasonably surmise that the hybrid hardware we sampled will arrive underneath new sheetmetal, bringing with it a different driving experience.

Making Sense Out Of A Topsy-Turvy World

If nothing else, our stint with the Cayenne Hybrid S served to reinforce that we live in interesting times. General Motors, once the world's largest automotive power, is on the brink of bankruptcy. Hyundai, a Korean company, are the orchestrators of this year's reigning North American Car of the Year – a rear-drive luxury sedan, no less. And we've just driven an electrified Porsche truck whose raison d'être is better fuel economy and lower emissions.

Say what you will about Porsche bringing the Cayenne to market in the first place, but having driven damn near every derivation of the vehicle ever sold in the States, this author can say it remains a startlingly omniscient piece of machinery capable of just about anything -– and now, a remarkably green performance. While the looks of the Cayenne and its button-crammed interior have yet to grow on us, its performance on the street and on Porsche's balance sheet has proven to be nothing to sneeze at. The model line's 250,000 unit sales history has given Porsche the development dollars to continue advancing enthusiast-oriented models like the 911 and Boxster, while allowing it to become one of the world's most profitable and powerful automakers. If Porsche has to add a little green to its otherwise blue blood to keep churning out 911 GT2s and Cayman S coupes, so be it – the Cayenne Hybrid S has a lot to recommend it.

I'm reporting this comment as:

Reported comments and users are reviewed by Autoblog staff 24 hours a day, seven days a week to determine whether they violate Community Guideline. Accounts are penalized for Community Guidelines violations and serious or repeated violations can lead to account termination.

    • 1 Second Ago
      • 6 Years Ago
      Can anybody explain why every single hybrid full-size SUV needs to have "H Y B R I D" spelled out across its rocker panels in a gigantic, gaudy vinyl decal?
        • 6 Years Ago
        Because its not enough that it is a Porsche. Its a hybrid Porsche like whoa! Porsche makes hybrids!? Same reason some cars have a type R, M, AMG, RS, F, SS, SHO, and other badges to differentiate itself from the norms.
        • 6 Years Ago
        Because how else will people know that you're doing something good(less bad) for the environment! Because what's the point of driving a Hybrid if people don't know it's a Hybrid!?
        • 6 Years Ago
        I think GM did some research that said people who buy Hybrids want people to know they are driving a hybrid. That's why something like the Prius is so popular while the Civic/Accord/Camry Hybrids aren't.
        • 6 Years Ago
        Because the people who buy them need all the help they can get.
      • 6 Years Ago
      why do so many people leave comments without actually reading the article?? There's a whole paragraph about the "hybrid" branding and how Porsche will play it subtle and the decals won't be mandatory.

      I've always thought luxury SUVs were a bit of a contradiction, and one attempting to be fuel efficient seems even more so. That said, there's a lot of room for improvement, and a hybrid drivetrain can do a lot of good on a vehicle this size. Either way, it's great to see Porsche is actually going at it. It'll be neat to see if they can pull off a decently performing hybrid 911 some day down the road.
        • 6 Years Ago
        Can you imagine the uproar?!
      • 6 Years Ago
      Bring the F*ckin Diesel!!!!
      • 6 Years Ago
      Nice spare wheel.
      • 6 Years Ago
      This must be the most disgusting product Porsche has ever produced. Not only is it a truck, from a storied sports car maker, but it is also a friggin' hybrid, the least sporty powertrain configuration available. The only way it could be worse would be if it was FWD and had a CVT.
      • 6 Years Ago
      That's great. It can turn off the engine when decelerating. The only problem is you can't get anywhere by decelerating. Cars spend most of their time accelerating, or in steady state.

      Also, why does this car get a free pass for the sticker on the rocker panels? The article say it isn't mandatory on this unlike the GM vehicles? It's not mandatory on the GM vehicles either. Articles on ABG and I think on here mentioned, GM will remove the decals from your hybrid SUV before you receive it at no charge and without having to get a note from your mom. Doesn't seem any more mandatory than these are to me.
        • 6 Years Ago
        Point of clarification:

        The difference with Porsche's system is that by decoupling the V6 entirely, there's no parasitic drag from the engine, and the hybrid electric motor can then push along the Cayenne along, largely maintaining vehicle speed (even at highway velocities), for far longer than simply coasting. Systems from other automakers (Toyota, GM, Ford, etc.) don't have this capability.
        • 6 Years Ago
        Chris, that's wrong.

        Every 2-mode system has this capability or equivalent, including GM's and Toyota's. Non 2-mode systems like GM's BAS system and the Honda IMA system do not have this capability.
      • 6 Years Ago
      I see Porsche is trying to channel the Yukon Hybrid massive letters design cue.
      • 6 Years Ago
      Like Jay Leno said in the episode of Top Gear when clarkson's buddy drove the honda FCX in California..."Americans want people to know the anonymous good they are doing". I for one can't stand stickers period and literally want to kill myself everytime i see this gaudy junk

      side note: who ever said it was ok to put bumper stickers on BMW's..saw one today on a 5 series and I almost died.
      • 6 Years Ago
      As useless as this 'truck' is, it's nice to see the 3.0T hybrid drive making towards production, an S4 or S5 hybrid might be pretty entertaining (40-50% fuel savings vs the current 20% the supercharged V6 offers).
      • 6 Years Ago
      So... VW Toureg hybrid?
      • 6 Years Ago
      When reading the opening paragraph about the abrupt engine cut-off, did anyone else think of the Batmobile chase scene from "Batman Begins" ? Anyone...?

      On topic: I'm more impressed by the system itself, than the fact that it's in an SUV. I'm intruiged that they only feel like they're 90% complete on what sounds like a pretty solid system. It makes me wonder what that other 10% would include; I won't pretend to know that much about hybrid mechanics, but if this system could somehow be combined with a kinetic or pneumatic hybrid system (for gas-less acceleration), that would be a huge plus point. Anyone who could answer my question please weigh in, as I'm honestly curious.

      Regardless of this system being wasted on an SUV, I still tip my hat to Stuttgart's finest, and I'm definitely excited to see these in person.
      • 6 Years Ago
      Hey! Porsche can do massive tacky Hybrid stickers on the side too, just like GM! What better company to emulate these days?!
        • 6 Years Ago
        I'm guessing it's a press car livery but you never know...
        • 6 Years Ago
        I'm guessing you're wrong. Read the article.
    • Load More Comments