While the GT3 R Hybrid’s generator-based KERS technology has nothing to do with the battery-based hybrid setup in the Cayenne S Hybrid, it’s a good bet the electric racer exists largely to promote the idea of alternative Porsche power. That Stuttgart is committed to the concept is obvious, as its latest take on an eco-friendly drivetrain looks and feels like a mature technology.
Open the compartment under the luggage area and the 176-pound, maintenance-free, Nickel Metal-Hydride (NiMH) battery pack looks fully integrated into the vehicle package. The only downside is a loss of the supplementary underfloor
The Cayenne S Hybrid is a “parallel full hybrid,” or a hybrid with two powertrains that can operate independently or together. Its internal-combustion engine is a 333-hp, supercharged 3.0-liter V6 developing 324 lb-ft of torque from 3000 to 5250 rpm. The synchronous electric motor produces 47 hp and a whopping 221 lb-ft of torque up to 1150 rpm, making for a total system output of 380 hp. The combined torque peak of 428 lb-ft comes only at 1000 rpm — because the torque of the electric motor diminishes as that of the V6 increases.
There are three power modes: combustion engine only, electric only (if the battery has enough charge), and a combination. A Hybrid Manager, whose electronic brain controls the separator clutch that activates or deactivates relevant drive units, chooses the appropriate mode.
The hybrid gear makes the S Hybrid 540 pounds heavier than a base 2011 Cayenne. The 4,938-pound, dual-fuel Cayenne is 154 pounds heavier than a range-topping Cayenne Turbo, so it’s the heaviest Porsche to date. Its combined thrust delivers a more Porsche-like experience than you’d expect, however: 0–62 mph in 6.5 seconds, 0–100 in 16.5, and a top speed of 150 mph.
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.
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.
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.