The smaller engine’s reduced capacity is a result of a larger, reinforced crankshaft that shortens the engine’s stroke, and you only do that if you want to put more power through it, such as the 440bhp made in the Panamera S. So there’s clearly a hotter Panamera hybrid on the way.
The Cayenne has no such need, so is denied the smaller, stronger engine. Still, the 3.0-litre unit can generate 335bhp all by itself, to which a further 134bhp of power is added from the electric motor - and that's, indeed, identical to that used by the Panamera.
Total system power therefore amounts to 469bhp. Which sounds good until you realise that while Porsche is making no official claims for this as-yet-unhomologated car, the hybrid system in the Panamera adds 320kg to the weight of the standard car and there’s no good reason why the same (or similar) will not be true for the Cayenne.
The other difference is that while all Panameras have Porsche PDK dual-clutch gearboxes, all Cayennes have conventional eight-speed automatics. This might not sound too important in the context of a hybrid, but, as I found out in two days of roaming around South Africa in one, it quite demonstrably is.
I can’t tell you how quick it is but, with substantially more power and torque than the old Cayenne Hybrid, I’d estimate a 0-62mph time of a little over five seconds and a top speed of a little less than 160mph. So quick enough, in other words. It should do around 25 miles on electrical power alone – five fewer than the lighter, lower, more slippery Panamera – and 84mph, rather than 87mph, on electricity alone.
But you notice the extra weight less in the Cayenne than in the Panamera; I guess because your dynamic expectations are more modest for a luxury SUV. What you notice far more is how much smoother this powertrain is. All the joins between internal combustion and electrical power are smoothed over by the ZF box in a way the Panamera's PDK cannot manage.
The result is that the big off-roader actually feels more sophisticated than the closest thing to a limo Porsche has ever built. The electric drive system will also prove a boon for those few owners who go off-roading because there’s never been a more precise, easily regulated way of controlling a car’s speed to the fractions of a mile per hour required for rock-hopping.