Porsche is relatively low-key about the ongoing success of the Cayenne. As one of the most profitable cars in its line-up, the big SUV arguably helps bankroll the suite of classic sports cars that are more readily associated with the Porsche name. As a result the vociferous opposition to the car that greeted its introduction back in 2002 is on the wane and the addition of another four door - the Panamera - in 2009 bolstered the status of the bigger car. We're now well into the lifecycle of the second generation Cayenne and its popularity is undimmed. There's even a smaller Porsche crossover in the works, dubbed the Cajun, pitched at those who can no longer squeeze their children into a 911's skinny rear seats but who can't quite make the mental leap to owning a 4 x 4.

While the purists and the realists battle it out, Porsche's engineers have been quietly turning this hefty machine into a deft-handling beast. Even more importantly, they've been using the Cayenne as a testbed for future tech. It's ironic that what was initially seen as the company's most lumbering and politically incorrect product should now be at the vanguard of technologies meant to soften the environmental blow of its range. Not only was the Cayenne the first Porsche with a diesel engine it was also the first hybrid in the range (there's now also a Panamera S Hybrid). Announced last year, the Cayenne S Hybrid mates electric motors to the V6 engine, with a host of clever systems for saving as much fuel as possible.

Porsche recently discovered to its delight that one of Ferdinand Porsche's earliest automotive experiments, the Semper Vivus from 1900, could safely be dubbed the 'world's first hybrid.' The company promptly set about creating a precise replica of the machine to exhibit alongside its new generation of hybrid sports cars, 111 years later. This convenient little piece of automotive history dovetails into the way hybrid power is now used to take the edge off the company's largest models.

So how does the Cayenne S Hybrid stack up and is it still a real Porsche? That latter question is somewhat subjective, and its safe to say that the difference between the Carrera GTS and this automotive behemoth is still substantial. The hybrid powertrain is so subtle as to all but unnoticeable in everyday use, except when gliding silently and electrically off the line (range on all-electric power is only a few miles) but the car still feels fast, especially given its size. It's a great place to sit - the interior is one of the best in its class - but the driving experience is a strangely hollow one. In any Cayenne you're never sufficiently involved in the driving to get over that lofty SUV feel and the S Hybrid exacerbates this strange dislocation. You're also never in any doubt about being in one of the biggest, most ostentatious cars on the road, however well cosseted you are from life on the outside.

Ultimately, though, we suspect that those in the market for a Porsche SUV will go the whole hog and get the unashamedly bold and boisterous Cayenne Turbo, while those seeking a gliding, hybrid-scrubbed low emission 4 x 4 will probably be more suited to Lexus ownership. But if you have to have a four door Porsche with as minimal a footprint as possible, the new Panamera Diesel is a somewhat better bet. It looks like it's down to the Cajun to help Porsche's faithful conquer their innate sizeism.

TAGS: PORSCHE