First drive: Electro-Cayenne to lead hybrid Euros

PORSCHE is odds-on to become Australia’s first European brand to offer petrol-electric power as the German manufacturer and its Audi and Volkswagen affiliates introduce their first full-scale volume production hybrid vehicles within the next three years.

The Stuttgart marque will debut its hybrid technology in the Cayenne with a V6 engine “by the end of the decade” and GoAuto was part of a select gathering of the world’s motoring media invited to experience cutting-edge hybrid technology for the first time in Germany last week.

Although company executives won't be more specific, with the next-generation Cayenne due for release around 2010, it would be logical for Porsche to introduce both the new model and the hybrid version at its home motor show in Frankfurt in September 2009.

Within months, Volkswagen will introduce its Cayenne-based Touareg hybrid and Audi will apply the technology to its bigger Q7 SUV, but a decision on which of the three vehicles will be first to market will be determined at board level.

It could be an interesting battle, but one Porsche is likely to win – not least because it is the major shareholder in VW (30.9 per cent) and Audi is a wholly owned VW subsidiary.

“We are discussing what car is coming when,” Cayenne Hybrid project manager Dr Michael Leiters told GoAuto at the company’s Weissach technical centre near Stuttgart last week.

“But at the end there won’t be a time of one year or even half a year (separating) these cars – I expect we will come very close together.” The three SUVs will be the first vehicles to employ a ‘full’, or ‘parallel’, hybrid driveline, with both the petrol engine and the electric motor driving directly through a regular six-speed automatic transmission (rather than the constantly variable transmissions used in most current and planned hybrids).

Audi’s Q7 hybrid may feature a V8 engine rather than the 3.6-litre 206kW V6 of its smaller Porsche and VW siblings.

Porsche expects a hybrid take-up rate of between five and 15 per cent for Cayenne, which indicates annual sales of between 2000 and 6000 units globally at the current sales rate.

Within a year or two of releasing the Cayenne Hybrid, Porsche will also produce a petrol-electric variant of its forthcoming four-door, front-engined Panamera GT car, which employs the Cayenne platform and will be launched in regular petrol variants in 2009.

Presenting a new vehicle concept to the media several years prior to its introduction into the market indicates how seriously Porsche is taking hybrid, which is necessary to not only push its green credentials but also to meet US legislative requirements.

Toyota has long been the global hybrid leader, which has enabled Lexus to take the high ground in the premium and luxury sectors with vehicles like the GS450h, RX400h and LS600h (due here in October), but the Europeans are fighting back with what they claim is more advanced technology.

Even BMW and Mercedes-Benz – both of which view hybrid as a stop-gap measure before hydrogen becomes viable – are working together with General Motors on a range of hybrid vehicles. These will soon start appearing overseas but are not expected to be available in right-hand drive before about 2012.

Porsche’s hybrid system has been developed jointly by all three partners at VW headquarters in Wolfsburg.

It was initially previewed by Audi in the form of a 4.2-litre V8 Q7 hybrid concept vehicle at the Frankfurt show in 2005. Audi previously built two ‘plug-in’ hybrid models called Duo (in 1989 and 1998), but production is believed to have been fewer than 100 vehicles.

Dr Leiters told GoAuto that it was important for Porsche to show its production hybrid system ahead of VW and Audi because Porsche prides itself on being a technology leader.

He told us that it is also more important for Porsche to use hybrids to establish its green credentials in the current climate because, unlike its partners, it does not offer small cars or diesel engines.

And, while the hybrid Cayenne provides improved acceleration over the regular V6 model, Dr Leiters said that the main motivation was to reduce fuel consumption rather than boost performance.

“We were searching for a solution that would do both, but the main focus is on fuel reduction,” he told GoAuto. “We are convinced there is a market there for hybrid. We didn’t do it to follow the hype, we did it with a serious strategy. We have to ensure the social acceptance of the brand and to meet future laws.” Porsche recognises that the Europeans have been left behind by Japanese manufacturers in the field of hybrid technology.

“Today, the term ‘hybrid drive’ is linked primarily with the name Toyota, and not with Porsche or any other German or European manufacturer,” Dr Leiters noted in his official address.

“In recent years German manufacturers have pursued other strategies to reduce fuel consumption than their Japanese competitors – but it is equally true that German manufacturers have no need to hide away from the Japanese.

“Our company has invested a three-digit million Euro amount (more than A$1.7 billion) in the last 10 years alone in the optimisation and ongoing development of drivetrain technology. However, we are reaching the limits of physics in the development of large engines for large upmarket vehicles.

“This is why we have kept a very open mind to hybrid technology right from the start, very carefully analysing the activities of other manufacturers, in particular Toyota, and joining forces with appropriate partners in development at an early point in time.

“We were not even put off by the fact that to this day no manufacturer has arguably made any money on hybrid drive.

“Considering the worldwide climate debate and new legislation in the pipeline, we are convinced that customers will become much more sensitive to the environmental compatibility of their cars in future, changing their purchasing behaviour accordingly.

“Particularly a premium manufacturer like Porsche must therefore offer competitive powertrain solutions with low fuel consumption and emissions, since otherwise the social acceptance of even a strong brand such as Porsche would start to weaken and lose credibility, which in the course of time would mean a loss of market share.

“Hybrid technology offers significant benefits, particularly in urban stop-and-go traffic, with a decrease in fuel consumption under real-life driving conditions of up to 25 per cent. Indeed, this is also why numerous potential Porsche customers now wish to have hybrid drive in their cars.” The prototype Cayenne Hybrid produces a fuel consumption figure of 9.8 litres per 100km – an improvement of 23 per cent over the standard petrol V6 Cayenne’s 12.9L/100km under the New European Driving Cycle (NEDC) regime.

However, Porsche’s engineers are confident that continuing development will result in reaching the production target of 8.9L/100km.

The key to reaching the lower level is development of lithium ion batteries, which are about 50 per cent lighter and more powerful than the existing nickel metal hydride batteries, as well as being cheaper. But there remain technical challenges with lithium ion batteries and they may not be ready for production until beyond 2010, according to electronics engineering manager Dr Wolfgang Herdeg.

Before going to production, the battery must be guaranteed for “life” – which Porsche regards as 200,000km under the worst possible conditions. For other Porsches, that figure is officially 240,000km, but in the real world it is obviously far higher.

Regardless of which battery is finally used, it will be located in the rear of the vehicle in place of the spare wheel, resulting in no reduction in cargo space or fuel tank size. Instead of a spare, Porsche will include a puncture kit and a compressor – as it does in its sports cars.

Cayenne Hybrid in detail

THE secret to Porsche’s Cayenne hybrid system is an in-built disengagement clutch and complex electronics that enable the combustion engine to be engaged and disengaged almost imperceptibly.

With a computer processing capacity of 20,000 data parameters, compared with 6000 for a regular engine and transmission, the VW Group partners have resolved the technical issues that have discouraged other car-makers from adopting the parallel hybrid system.

The Cayenne Hybrid uses its normal 206kW 3.6-litre V6 engine and six-speed Tiptronic transmission, with the 34kW electric motor and disengagement clutch housed between them.

This not only enables the Cayenne Hybrid to idle along using only electric power, it can also silently coast down a gentle slope at speeds of up to 120km/h with the combustion engine turned off. Just prod the accelerator and the engine starts driving again, but with no jerking as it reconnects.

Performance is enhanced over the regular V6 Cayenne because the electric motor adds some 285Nm of torque to the engine’s normal 375Nm – giving it more torque than the V8-engined Cayenne S up to 3200rpm.

With more than 500Nm of torque on tap from 800rpm to 3200rpm, the Cayenne Hybrid accelerates from 0-100km/h half a second faster than the normal V6 version.

As with other hybrid systems, it uses electric powered steering and air-conditioning systems, as well as recuperative braking to assist recharging the battery. Porsche claims the electro-hydraulic Servomatic steering system meets its demanding requirements for feel as well as response, even with high-speed swerving.

Air from the vehicle’s climate-controlled interior is blown into the battery compartment to keep it cool and thereby extend its service life.

Cayenne Hybrid drive impressions

GETTING to ride in a new model more than two years ahead of production – let alone one bristling with new technology – is a real treat for any motoring writer, but that’s exactly what Porsche provided GoAuto at Weissach in Germany last week.

What’s more, we were able to ‘drive’ one of the prototypes on the company’s rolling road test bed, where fuel consumption and emissions testing is conducted.

So what is the Cayenne Hybrid like? Well, it’s a lot like a regular Cayenne, but with moments of eerie silence.

Starting the car involves absolutely no sound at all because the petrol engine does not fire into life until you hit the throttle with a little force.

Drive away from standstill with only a light throttle and you only get electric power, so the vehicle moves along silently at up to about 30km/h. Better watch out for pedestrians because they don’t hear you coming.

With more speed and throttle, the V6 engine kicks in imperceptibly, thanks to the complex electronic control system and the innovative disengagement clutch, which allows slippage for about three-tenths of a second so that the revs of the engine and electric motor align.

Floor the throttle from a standing start and the engine not only fires up almost instantly but, with the electric assistance, races to 100km/h half a second faster than the regular V6 Cayenne, despite carrying an extra 150kg. In fact, it’s almost as fast as the V8 Cayenne.

Porsche talks of the car “sailing” on electric power only at speeds of up to 120km/h, but this is a little misleading and some people have mistaken it to mean cruising (maintaining speed on a freeway, for example).

But it is not cruising it is really coasting – the difference being that you need to be coasting downhill because, if the road is flat, the electric motor alone is not powerful enough to drive the big Cayenne against the force of air and road resistance.

Nevertheless, it is an impressive experience – and an economical one – to coast along silently and then hear (but barely feel) the engine kick in as you squeeze the accelerator again.

Cutting the engine under deceleration reduces engine-braking, of course, and we understand that for the production version Porsche is considering an over-ride of this engine-cut facility when ‘Sport’ mode is selected to electronically sharpen the transmission and suspension settings.

The prototypes we experienced have a power transfer read-out in place of the central sat-nav screen so you can see the power flow between electric and/or engine, and when the regenerative braking system is charging the battery.

Porsche may offer this screen as a selectable menu item when the vehicle goes into series production.

Otherwise, the only internal indication that this is a hybrid vehicle is a battery charge indicator level located on the right side of the instrument binnacle.

Of course, we were unable to assess the handling and braking of the heavier hybrid, but the engineers naturally assured us it will be as good as the regular Cayenne.

The rolling road drive, in which we completed a simulated 3km around Stuttgart that forms part of Porsche’s actual test route for real-world fuel consumption, proved how ‘normal’ the Cayenne Hybrid is to drive.