What is it?
This is Porsche’s answer to the Lexus RX450h, and the first hybrid model to enter Porsche’s range. The Cayenne Hybrid uses a parallel system that combines a 46bhp (33kw), 221lb ft electric motor with a 333bhp supercharged V6 petrol engine. Either can power the car independently, with the electric motor capable of propelling the Cayenne up to 37mph without any aid from the combustion engine.
If you want to access the full performance potential of the Cayenne, the electric motor works in conjunction with the V6 to put out the maximum combined 380bhp and 427lb ft, when the Hybrid is capable of 0-62mph in 6.5sec.
Automatic stop-start also kicks in to cut emissions and consumption around town, and works very effectively given that the engine start-up is almost entirely free of vibration should you want enough acceleration to wake the petrol engine. Or if you’re happy to settle for more sedate progress the electric motor will drive the Cayenne in complete silence.
The hybrid and diesel Cayenne models get different all wheel drive systems to the rest of the range, with power split 60-40 front-to-rear in normal conditions, with a self-locking centre differential allowing power to flow between axles depending on available traction. The new, eight-speed torque-converter Tiptronic S gearbox also features as standard on the hybrid Cayenne.
All of which results in the headline figures of 34.4mpg and 193g/km.
What’s it like?
Extremely effective. The real benefit to the hybrid system, apart from the fuel savings, is the refinement. Around town the system regularly propels the Cayenne on pure electric power, resulting in eerily silent progress, and though (as with all current hybrid systems) you have to be extremely careful on the throttle and be willing to infuriate following traffic if you want to pull away from a standstill without triggering the V6 motor, it is nonetheless quite possible to cover a useful urban distance without ever using any petrol.
Driving normally will result in regular interaction between the petrol and electric motors, and it’s impressive that the transition between the two is barely noticeable. There’s ample flexibility to make the Hybrid an enjoyable and relaxing urban and motorway tool, thanks as much to the eight-speed gearbox as the powerful motor.
The Porsche hybrid system also boasts an extra element of technical wizardry, in that it has the potential to disengage its combustion engine and 'sail' at anything up to 97mph.
In practice, this means that taking your foot of the throttle and simply allowing the car to roll along will trigger the separator clutch and the V6 motor will stop running. Because there is no engine drag causing resistance, and because in this state the electric motor delivers a stream of power, the Cayenne can run for good distances without using its petrol engine. It can feel slightly disconcerting initially, but with familiarity this becomes one of the most useful abilities the Cayenne hybrid offers.
The standard steel springs on the hybrid don’t manage to restrain body roll as well as the more sophisticated air suspension (which is available as a £2330 option), with body float noticeable over undulating surfaces. But the suspension still does a decent job of absorbing most interruptions in the road surface.