Sports cars are supposed to be compact, agile and quick machines, with the focus placed firmly on performance. For that reason, your typical sports car formula allows for two seats, a powerful engine, wieldy dimensions and race car-inspired handling.

As sports cars go, few can claim to be as iconic, nor as enduring, as the Porsche 911. But while the 911 does follow the rule book in terms of size, weight and performance, it also makes nonsense of convention by hanging the engine behind the rear wheels.

Not that Porsche has ever been a company to follow the rules. After all, it was the Zuffenhausen marque that pioneered the now established trend of high-performance SUVs when it launched the Cayenne. The purists were up in arms, but Porsche is still smiling all the way to the bank.

So, the emergence of the Panamera Sport Turismo should hardly come as a surprise. It’s a natural adjunct to the established Panamera line-up, but adds the extra space and versatility of an estate-type vehicle to the normal version’s existing virtues.

At this point, I should make it clear that I’m a traditionalist when it comes to sports cars. I’ve lusted after the purity of spirit and intent epitomised by the 911 as long as I can remember, and I was one of those who cried foul when Porsche confirmed its SUV intentions.

The success of the Cayenne proved me wrong while underlining that traditional motoring categories don’t always apply. The Cayenne managed to retain enough of the sports car maker’s DNA to warrant the Porsche badge all the while offering SUV-style utility and versatility.

In some ways, it was easier to accept the Panamera as a larger, four-doored alternative to Porsche’s sports car offerings when it first appeared. And if the emphasis had shifted a little further towards the comfort and luxury side of the automotive equation, its makers ensured that there was always enough poke and stomp to keep performance fans happy.

Considered in that light, making the leap from Panamera to Panamera Sport Turismo is perhaps less challenging than one would expect. Yes, it’s a big machine – imposing even – when first encountered.

But if you’ve sampled the Panamera’s virtues, then the Sport Turismo adds a bit more on the space and versatility front, without taking any of the already established Porsche-ness away. In fact, there’s something irreverent about the Panamera Sport Turismo that should please those with a penchant for individuality.

It thumbs its nose at the conventional bigger-is-better SUV crowd, acknowledges that few luxury SUVs ever swap for gravel, and presents an alternative that is, well, just that little bit different.

In styling terms, it’s hard to call the Panamera Sport Turismo a thing of beauty. Majestic, yes. And commanding. After all, at just over 5m long and 1.94m wide, this is a beast of a machine.

And yet, it retains the low-slung stance, the wide tracks and the short overhangs that typically contribute to the almost menacing demeanour you’d expect of a Porsche.

The front end with its oblong headlights, curved nose, profiled bonnet and gaping ducts is certainly typical of the marque, while the quad-LED daytime running light signature is distinctive. The recessed air vent along the flanks is a trait shared with the normal Panamera, but the rear is uniquely Sport Turismo.

The roofline extends further back, culminating in a large, motorised tailgate that opens wide and deep to provide full and convenient access to a huge cargo area.

Not immediately apparent is the presence of an active roof spoiler, integrated into the tailgate. It deploys automatically, depending on vehicle speed, and can add up to 50kg of downforce at the rear.

Dual tailpipes jut out on either side of a tidy rear diffuser, while the taillight clusters are linked by a horizontal LED strip.

If you’re interested in a car like the Panamera Sport Turismo, interior space and execution will be priorities – and it’s one of this Porsche’s brightest attributes. I’ve already mentioned the cavernous cargo area which will swallow 520 litres of luggage – and 1,390 litres if you’re uncouth enough to load it to roof height.

But it’s the unusual rear bench seat that should attract a lot of attention: in standard trim, it has a three-seat configuration – a Porsche first. Theoretically, it makes the Sport Turismo a 4+1-seater, although I think most owners will stick to the full four-seater arrangement.

Regardless, there’s oodles of space for two or even three occupants. If you didn’t know better, it would be easy to believe that you’re in a stretch limo. Legroom is copious, and despite the curved roofline, even tall folk are easily catered for.

In a long-wheelbase BMW Seven or a Mercedes-Benz S-Class, you’d imagine most of the emphasis to be on the rear occupants, leaving the mundane task of actually driving the vehicle to the chauffeur. But this is a Porsche, and the good news is that the emphasis remains on the pleasure of piloting the Panamera.

Thus, the cockpit is still the Sport Turismo’s command centre, and the driver is very much the captain at the helm. The ergonomics fuse tradition with cutting edge, delivering the rev counter-centric gauges so intrinsically Porsche in a binnacle ahead of the driver, but flanked by a large, high-res touchscreen display that stretches the full width of the centre stack.

The display offers intuitive and flexible control of the Porsche’s vast feature set, encompassing everything from climate control and audio to satnav, Bluetooth telephony and a host of vehicle settings. Key controls are also conventionally presented, allowing intuitive access when it’s more important to keep your eyes on the road than navigating on-screen menus.

Either way, what seems a little convoluted and complicated at first soon becomes familiar territory. This is not a car that intimidates with tech, but one that invites driver and occupants to explore and embrace what’s on offer.

Being a Porsche, it’s the dynamic capabilities of the Panamera Sport Turismo that must take centre stage – and any fears that this might be the big machine’s Achilles heel are soon allayed.

As tested here, the 4S Sport Turismo is home to a beefy, bi-turbo V6 rated at 324kW and 550Nm. That’s a lot of muscle – but then, it has to move around 1.9 tons of metal. The gearbox is an eight-speed PDK dual-clutch transmission, directing the engine’s urge to all four wheels.

Porsche has got the gearing just right, making the most of the vast, wide torque band to make the Sport Turismo feel eager in every gear. The test car’s Sport Chrono pack, together with Sport and Sport Plus modes (as well as adaptive suspension) all conspire to ensure that there’s never any doubt about the big four-door’s dynamic capabilities.

And yes, this is a fast car by any standard. It gets off the mark with little fuss but plenty of shove, thrusting you back in the high-backed bucket seat and accelerating with a tenacity that never seems to let up.

Yes, it’s true that the sheer weight of the car, and its rock-solid stance, seem to underplay just how quickly you’re actually gathering – and maintaining – pace. Thankfully, Porsche hasn’t forgotten the need for a soundtrack to match the action, and despite the turbo assistance, the engine sounds eager and hungry enough to add to the experience.

Arguably the most impressive aspect of the Panamera 4S Sport Turismo is its composure and wieldiness when straight tar gives way to twistier stuff. I expected the car to feel its size when pushing into corners, but this is where the four-door shows its sports car class.

Thanks to clever management of the all-wheel-drive system, and (optional) rear axle steering, the big Porsche toes the line with gravity-defying enthusiasm. The car’s attitude remains flat and focussed, while the steering delivers ample feedback.

For all its size and weight, the Panamera Sport Turismo initiates a close line of communication with the helmsman, providing plenty of tactile confirmation and responding keenly to driver input. The result is a car that’s both entertaining and reassuring to drive with gusto.

The stats confirm that this Porsche belongs in the performance league: 4.2sec for the 0-100km/h dash, 10.sec for the 0-160km/h sprint, and 16.1sec to get to 200km/h from rest. But it’s the way this Panamera conducts itself when given stick that never ceases to amaze.

Of course, the Panamera Sport Turismo also offers relaxed, long-distance cruising, cosseting its occupants in climate-controlled comfort. But you always know that the Porsche personality is only one stomp of the loud pedal away.

In a country obsessed with big, muscular, luxurious SUVs, the Panamera Sport Turismo 4S might take some convincing. But once you’ve experienced its adeptness and driver appeal, together with its unique expression of the Porsche DNA, it might just prove to be a very real, and tempting, alternative to convention. DM

PROS

Unique combination of limo-style space and luxury, linked to pulse-quickening performance.

CONS

Many might prefer a high-performance SUV.