Porsche Cayenne S E-Hybrid 2015 Review - International

Toyota was once the darling of hybrid providers. But the expectations of the world’s drivers, of legislation and of crowded cities mean plug-ins are the go-to hybrids of the immediate future.

And guess which car-maker has the most plug-in hybrids in its line up? No, I probably wouldn’t have guessed Porsche, either, but for now, it’s true. It has the 918 (which only just qualifies as a production car), the Panamera S E-Hybrid and now the Cayenne S E-Hybrid.

Odd, then, that Porsche and Toyota should be going head-to-head in the World Endurance Championship in hybrids of very different designs, but back to the Cayenne S E-Hybrid.

It’s a Cayenne with a combination of the Audi S5’s 3.0-litre supercharged V6 up front, a 70kW disc-shaped electric motor between the V6 and its eight-speed torque-converter automatic transmission and an aft-mounted 10.8kW/h lithium-ion battery pack.

And, with the Panamera S E-Hybrid already in Australia, Porsche has big plans for the the plug-in Cayenne, which will arrive some time after the regular facelifted Cayenne line-up (due here in November), priced at $139,200 plus ORCs — more than $10K less than the Cayenne hybrid it replaces and just $700 more than the twin-turbo V6-powered Cayenne S.

The old-school motor gives up 245kW of power from 5500rpm up to 6500rpm and has 440Nm of torque from 3000 revs to 5250. The new-school motor has 70kW of power from 2200 to 2600 revs and 310Nm from zero.

Combined, they offer up 306kW of power at 5500rpm and 590Nm from 1250 to 4000 revs, and they are far more Porsche-like outputs than each motor offers individually.

It’s enough, Porsche claims, to move its Cayenne S E-Hybrid to 100km/h in 5.9 seconds, through to 160km/h in 13.7 seconds, through the standing quarter mile in 14.2 seconds and on to a 243km/h top speed.

Still on Porsche’s claims, it insists the Cayenne S E-Hybrid will pull just 3.4L/100km on the NEDC combined cycle, which is good for an astonishing 79g/km of CO2. Given its 80-litre fuel tank, that’s good for an even-more astonishing theoretical range of 2353km.

I say astonishing and even-more astonishing because of the absurd amount of weight these two motors have to pull.

Porsche was once quite good at making tractors. Tractors are heavy because they do heavy work and tow/push/drag/lift heavy loads. But Porsche doesn’t make tractors anymore.

That’s why it’s such a shock to stumble on the Cayenne S E-Hybrid’s 2350kg kerb (dry) weight in the specifications. With all due respect, nothing on the road today has the moral right to weigh 2350kg unless it’s doing work, like Porsche tractors once did.

One of the reasons it’s so heavy is that the powertrain adds a full 270kg on top of the V6 Cayenne S. So the Cayenne S E-Hybrid generates its numbers because, largely, of the strength of the electric motor and its ability to cover up to 36km as a pure electric car.

On top of that, it will also run up to 125km/h as an electric car, which is almost perfect for Europeans whose commutes include some autobahn/autoroute/autostrade running and plenty of city miles.

And while its powertrain is largely similar to the far-lighter Panamera S E-Hybrid, it’s not identical. That’s partly because it’s all-wheel drive (where the Panamera version is a rear-driver) and partly because its slightly later development allowed its engineers to use a new, higher-density battery that holds 10.8kW/h of juice compared to the Panamera’s 9.4kW/h in a battery pack of identical size.

The man in charge of the powertrain development, Manfred Schürmann, explained that the Panamera’s battery cells had 24.5 Amp/h of capacity, but the Cayenne’s new battery chemistry gives it 28 Amp/h.

“If this higher level of energy in the battery were in the Panamera, it would give it about 10 per cent more electric range,” he said. But it isn’t, and it doesn’t.

The Cayenne can recharge its battery in three and a half hours from a standard socket (via the cable inside the annoyingly large cable bag in the luggage area) or 90 minutes via an optional wallbox. It also suggests you should be doing that twice a day to gain the maximum benefit from the car’s potential economy, but admits a lot of people won’t do that.

Instead, they’ve fitted the car with a charging mode, where you push a button to make the V6 motor work harder (at the cost of between one and two litres/100km) to recharge the battery on the run.

But stronger battery or not, there’s no hiding the mass, nor the extra wind resistance and rolling resistance of the bigger SUV. Those pure-electric city miles will be best served without significant hills, because the weight of the Cayenne S E-Hybrid makes the car feel a world away from the electric zest of, say, the plug-in hybrid Volkswagen Golf GTE or the pure-electric BMW i3.

It feels sluggish on hills and can be found desperately needing the assistance of the V6, which kicks in once you prod past the détente that lurks about 80 per cent of the way into the throttle travel.

It’s for this reason alone that anybody who buys a Cayenne S E-Hybrid will struggle mightily to match the official numbers. If you want to buy a Porsche and drive it like a Porsche, the Cayenne S E-Hybrid isn’t the machine that will allow you to do all of that and refuel like you’re in a Polo.

We had a mix of city, autobahn and rural roads on our drive, with no major hills to speak of, and struggled to pull it down beneath 8.0L/100km, despite draining the battery completely.

We began in its electric mode, wafting silently through the highways and byways near Frankfurt airport, with the firm détente easily letting you avoid kicking the V6 into life.

It’s just not fast, though, and it’s demonstrably slower and less perky than the Panamera version. There will be situations where electric power alone won’t be enough to run with the prevailing traffic flow, especially when it’s pulling all that weight up hills.

That’s no biggie for performance, though, because you can just stomp through the détente to fire up the petrol motor. It starts up nicely and works effectively, even though there’s a significant and disappointing patch of coarseness between 3200 and 3400rpm on the way up the rev range.

Combine the two powerplants and any issues keeping pace with the moving machinery dissipate and it suddenly becomes like, well, a Porsche. You can still drive it for economy if you like, but just with less frustration.

You can cut out the middleman and just push the Sport button, which keeps the petrol engine buzzing all the time (as does the Charge mode).

When it’s running, the petrol motor lends the car aural character as well as pace, with the electric motor tangibly filling in the low-end torque gaps and letting it punch out of corners with more or less instant throttle response.

There’s genuine strength from idle onwards and while it does taper off above 5500rpm, you can just pull the shift paddle on the right to drop it back into the meat of the torque curve in a taller gear. Its urgency drops away beyond about 150km/h, but that’s hardly going to be an issue in Australia.

There are superb graphics built into both the central multi-media screen and the TFT info screen on the instrument cluster to tell you, very simply and clearly, how much charge you have, how much fuel you’ve been using, how much electric range you have left, whether the car is using or generating electrical energy (which it does while coasting or braking) and which motor is doing the driving. It does everything except give you an instant fuel consumption readout, which we found odd.

The trouble, though, is always that mass. It might go well in a straight line when all of the drums are banging but you know what the suspension is dealing with every time you turn the steering wheel.

It’s reasonably precise when it’s responding to the helm and there’s a surprising level of mid-corner grip here, too, but stringing together a series of corners is (in a very un-Porsche way) difficult and unsatisfying.

Its ride, though, actually benefits from the mass to make mince meat of anything, big or small, which tries to intrude on the cabin’s serenity.

There are some packaging issues that come with the Cayenne’s luxury, though. The biggest of these is the shallowness of the front passenger’s foot well, which sees even size seven or eight shoes rubbing their tips constantly against the under-dash plastic.

There’s also an intrusive lump sprouting from the transmission tunnel into the right-hand foot well, but that’s not going to be an issue with right-hand drive versions because the driver’s feet will be well forward of it.

It’s a technical powerhouse of an SUV, for sure, but it’s not the most economical in the real world. That honour would go to the diesel version.

Instead, it’s a legislation dodger; letting Porsche owners into congested cities guilt-free, claiming government rebates and tax breaks in countries that offer them. It’s not insignificant, attracting a $US5300 tax credit in the US alone, which more than makes up for the extra $US2800 it costs above the Cayenne S.

There are obvious benefits for those committed enough to plug it in twice a day, but how many of them are there, really?

If you don’t absolutely need a zero-emission car for 60 to 70km a day, buy the diesel. You’ll save money up front, you’ll save money in real-world driving and you’ll probably even have more fun driving it.

But if you want the very latest in Porsche technology, if you want to drive where you like without attracting the unwanted attentions of social commentators and if you want to take on the challenge of posting a 3.4L/100km figure on a tank of fuel, go right ahead.