Porsche Cayenne S E-Hybrid review

Thursday, 16 July 2015

The old adage of winning on Sunday and selling on Monday doesn't really stack up these days. Not when the racers bare little relevance to the vehicles in the showroom.

Tried buying a V8-powered Altima? Nissan's big sedan is about as sporty as an arm chair.

Segueing awkwardly to our subject here, Porsche re-entered the world of sportscar endurance racing last year with the 919, the hybrid formula enabling its motorsport efforts to advance its electrified road cars.

Motorsport improving the breed has been a core Porsche philosophy since it started racing in the early 50s. We can expect more hybrids too as greater electrification will be necessary for car makers to meet the coming emissions laws (in other parts of the world we mean) planned for the next 10 years.

After sampling the latest generation of Porsche hybrid technology, the electrified future won't be too horrid, rest asssured. 

Porsche has clearly learnt a few things of late; while its first Cayenne hybrid was an average effort, the new S E-Hybrid is a significant leap forward. The $175,300 petrol-electric joins the line-up of S models alongside the regular petrol S ($170,400, 3.6-litre V6 bi-turbo, 309kW/550Nm, 0-100km/h 5.5sec, 9.8L/100km, 2085kg) and the S diesel ($174,500, 4.2-litre V8 TDI, 283kW/850Nm, 0-100 km/h 5.4sec or 5.15sec in Louisson's hands, 8.0L/100km, 2215kg).

NZ buyers largely bypass the Cayenne S, most opt for the $187,700 GTS while the rest buy the S diesel.

The E-Hybrid is an unknown quantity at present. Blame the first one for being overpriced and underperforming, a general lack of knowledge around premium hybrids and that there are few financial incentives to buy a hybrid here.   

Time to shed some more light on this new hybrid then. It's a parallel plug-in version, and like the Panamera E-Hybrid, uses an Audi-sourced blown 3.0-litre V6 petrol with a synchronous electric motor sandwiched between it and the eight-speed auto. The E-Hybrid has a 306kW/590Nm combined system output with claims of 0-100kmh in 5.9secs and a hard-to-believe consumption average of 3.4L/100km. In standard form, it weighs in at 2350kg. 

The previous hybrid was rated at 8.2L/100km, the substantial improvement coming from the new electrical bits and pieces. Like the 10.8kWh lithium-ion battery in place of the old 1.7kWh NiMH device, while the motor is more powerful too, up from 34kW to 70kW. Where the old version had a minuscule EV range, the claimed distance here is between 18 to 36 kilometres, depending on your driving style and the nature of the terrain, and will operate in zero emissions mode at up to 125kmh. 

On start up, it defaults to e-power, aka EV mode, so long as the battery is sufficiently charged. The accelerator pedal has a variable pressure point, the first stop on the travel permitting maximum EV power without having to guess exactly when the engine will fire up. Push on past the detent and the engine comes on line to boost power. Flatten it to the floor past the next pressure point and you'll get e-boost and a further surge in performance as the full system output comes on stream. 

A Porsche racing philosophy is to keep things simple in the cockpit with minimal driver distractions, and so piloting the hybrid is hardly an overly complex procedure. Slot Drive and go basically. There are two hybrid-specific buttons; e-power or EV mode and e-charge where the engine is programmed to charge the battery. There are also Sport and Sport Plus buttons just like in a regular Cayenne. 

A full recharge takes about four hours on 240V with the standard 3.6kW charger. You can opt for a faster 7.2kW charger ($1640) but you'll need three-phase power installed. However, it will replenish the battery in 90mins. So it's all good in theory but what about in practice? 

After unplugging in the morning, we set out with a fully charged battery and managed 20 EV kilometres before it switched to its hybrid mode. We journeyed 57km in total to the test track, the average on the trip computer reading 5.5L/100km for the mix of urban, motorway and rural road running. The petrol engine cuts in and out often, the system making good use of engine-off coasting whenever it can. It regenerates volts on the move too when you decelerate, creating extra battery life. This it then uses to motivate you away from a standstill, taking this taxing load from the engine before it comes back on stream as you nudge past 30kmh or so. As such, 31.7 of those 57km were tailpipe emissions free. The trip computer has four screens to cycle through, helping you keep track of these things.  

We performance tested the E-Hybrid, falling short of the claim as the battery was done and so it was unable to generate the extra e-boost for full thrust. So 6.18sec was what we had to settle on while the full noise acceleration runs had the average up to 9.6L/100km. 

Our initial few kilometres up the reference hill road were e-boost free as well, the Cayenne performance feeling a tad underwhelming, but it didn't take long to generate some volts and the boost was back, giving the Cayenne a noticeable leg up. We probably should have run the acceleration times again, but the rains were a-coming, and we had some corners to lap up. For this may well be a hybrid but it's also a Cayenne. That means top-notch steering characteristics. It's a consistent communicator, the rack quick and precise, the weighting just right in the bends with even a touch of kickback to enhance the experience. Some EV/hybrid machines start decelerating quickly once you're off the go-pedal but here the motor regeneration is not overly aggressive, more like regular overrun. 

The hybrid gets air-springs and active suspension management. Click the Sport button and the ride firms to add a few bumps along the way but the reduction in roll is appreciable. The hybrid has a mechanical centre diff with a 42/58 front rear split rather than the S model's fully variable multiplate clutch torque transfer system and so it doesn't have the same rear drive feel to its progress. Still, it's a rare occasion when you'll push wide into understeer. This may be a hybrid but it isn't shod with ecotreads. It takes to twisting roads, though with the battery pack in the boot, you can feel the extra weight in the tail occasionally.

While the V6 doesn't provide an exactly awe-inspiring soundtrack, the auto does a fine job of gear selection. However, the brakes aren't quite up to Porsche's usual standard; they lack the typical bite we expect from the brand. But at least they provide a progressive feel, unlike the switch-like operation experienced in some EVs.

With the fun over, the trip computer was reading 16.5L/100m while once back at base, the rigours of the 140km round trip saw an average of 14L/100km, not bad for a sporting two and half tonne SUV. Boring crossover types can return similar numbers after testing. On the drive home, the 8.6km trip registered 11.2L/100km, 2.8km travelled with the engine off. Plugging in at work would be key to netting better figures.

The next morning a full charge returned 25 EV kilometres in dense traffic, the 33km urban trip averaging 3.9L/100km thanks to 27.1 EV kilometres. Like all hybrids, it works best in the city, and plugging in regularly is the key to optimising economy.

The hybrid doesn't surrender much of the Cayenne's abilities; same luggage capacity, same offroad ability, and it'll tow 3500kg if you option the Porsche tow bar which disappears up underneath the Cayenne at the touch of a button. There's no space for a spare tyre, and the cumbersome charger has no storage spot either. 

So why buy the hybrid? Are running costs really a concern when purchasing a $180k SUV? Probably not. And are Cayenne owners Green party members? Probably not either. We guess you'd buy it for its technology, or if you hate regular trips to the filling station, or maybe you have a carbon conscience yet still want some luxury. Whatever the reason it's now a more viable option but is still best suited for urban dwellers. Predictably we'd still want the GTS, or equally the Diesel S, while there's still the option.  

THE STATS

Model: Porsche Cayenne S E-Hybrid

Price: $175,300

Engine: 2995cc, V6, Supercharged, 245kW@5500rpm, 440Nm@3000rpm

Hybrid system: 382V, 10.8kWh, 70kW, 310Nm

Transmission: 8 speed auto, four wheel drive

Vitals: 6.18s 0-100km/h, 3.4L/100km, 79g/km, 2350kg

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