Even so, those merely admirable numbers belie its impressive pace on the fly. The intermediate-gear thrust with both motors engaged is impressive; you never feel like the S Hybrid lacks grunt in real-world situations. The 428 lb-ft torque peak at a low, low 1000 rpm helps the heavy SUV move away from rest briskly. It also compares favorably to the 406 lb-ft from 2000 to 2250 rpm in the new Cayenne Diesel and the 367 lb-ft from 3500 to 5300 rpm in the Cayenne S V8. Of course, with 516 lb-ft from 2250 to 4500 rpm on tap, the Cayenne Turbo is in a league of its own.
While its straightline performance is good, the S Hybrid does not feel as agile as its gas-engined brothers. The fact that its batteries and motors are positioned low helps, but you can feel the added inertia if you turn the steering wheel quickly. That said, because the new Cayenne platform is 396 pounds lighter than its predecessor, the S Hybrid is still relatively agile by still-impressive ur-Cayenne standards.
The S Hybrid’s brake regeneration and Auto Start Stop system work well, and its eight-speed automatic transmission is fast and seamless in its shifting. The S Hybrid’s electro-hydraulic power steering with servotronic control is a different system from the optional servotronic/hydraulic steering system found in other Cayennes, but it has almost as much feel and feedback.
Perhaps the most notable thing about the S Hybrid experience — other than the silent start-up — is a mode the Porsche engineers describe as “sailing.” If you’re driving along on a light throttle at up to 95 mph and the computer decides that the SUV doesn’t need much power to maintain constant speed, it will cut the V6 and switch to pure battery power. To the driver, the sensation is like coasting, but you’re actually moving along on pure electric power with no motor noise. It’s a weird feeling at first, but you get used to it. Depending on how much battery charge is available at the time, you can also engage this mode manually with the E-Power button on the center console.
Porsche has come a long way since I tried its prototype Cayenne Hybrid based on the first-gen Cayenne in 2007. Back then, the company spoke of 27 Imperial mpg, a pretty unremarkable figure against the outgoing BMW X5 3.0d’s 30 mpg. Thanks to serious platform weight reduction and advances in hybrid-drive technologies, the production Cayenne S Hybrid can log up to 34.5 mpg. In combination with its 193 g/km CO2 emissions, this SUV earns its spurs as a low-emissions vehicle (LEV) on both sides of the Atlantic.
Of course, the litmus for any hybrid is how it stacks up against its diesel equivalent in markets where both are sold. And, boasting 38.2 mpg and 195 g/km of CO2, the significantly cheaper, 308-pound lighter, oil-burning Cayenne Diesel trumps the S Hybrid, especially when purchase price and running costs are considered. The S Hybrid starts to make sense in the U.S. and Far Eastern countries, where the Cayenne Diesel is not available — though Porsche is said to be rethinking this.
For the time being, the Cayenne S Hybrid is significantly more economical than the Cayenne S or Turbo, and its torque peak comes in halfway between the two V8s — it’s certainly fast enough to see off most traffic. In the big picture, and Porsche engineers will admit as much, hybrids are an interim technology ahead of more advanced solutions. As hybrids go in the here and now, though, Porsche’s first is one of the better ones.