PORSCHE CAYENNE COUPé REVIEW

The largest changes between the Cayenne and the Cayenne Coupé are visual. Porsche's designers have grafted on a sloping rear roofline that chops around 20mm from the SUV's height, and added a few extra millimetres of length and width.

Credit where it's due, though, because their changes have helped shed some of the regular car's visual bulk. This isn't a jarring shape like the BMW X6; it's much subtler, giving the Cayenne Coupé more than a hint of slightly scaled-up Porsche Macan.

Elsewhere, you will notice that at the trailing edge of the roof there's a large fixed spoiler, which works in partnership with an active spoiler housed at the base of the rear screen. Capable of extending by 135mm, it's deployed at speeds in excess of 56mph, and is claimed to increase aerodynamic pressure over a rear axle that's 18mm wider. The wraparound rear light bar adds a bit of up-to-date retro-futuristic style commonly found on the Instagram pages of the fashionistas of today.

The Coupé has the same broad range of engines to draw upon as the regular Cayenne. That means there's an entry-level 3.0-litre V6 petrol model offering 349bhp of power, above which sit two V6 PHEV options (464bhp E-Hybrid and 513bhp S E-Hybrid) and then two further unhybridised V8 models (468bhp S and 494bhp GTS). At the top of the line-up is the V8 PHEV Turbo E-Hybrid, with a walloping 730bhp of 'total system' power.

All derivatives get electronically controlled four-wheel drive, and most sit on fixed-height steel coil suspension as standard, and two-valve PASM adaptive dampers. Height-adjustable air suspension is an option on lower-level models, and standard on a GTS and Turbo E-Hybrid, likewise a PTV Plus torque-vectoring rear differential. Active anti-roll bars and four-wheel steering remain optional on most derivatives.

Lock your attention onto the higher-end GTS and Turbo E-Hybrid versions of the car, meanwhile, and you can also choose between three weight-saving options packages that, in some cases, bundle up a lightened sports exhaust system with a carbonfibre roof and reduced sound insulation.

Climb into the Cayenne Coupé and you'll find not only a fractional reduction in space but also fewer seats.

In place of the standard car’s rear bench is a pair of individual chairs separated by a deep trinket tray and two cupholders - although a 2+1 layout can be ordered at no extra cost. On the plus side, the squabs have been lowered by 30mm, offsetting the lower roof, so adults can typically ride back here in good comfort.

However, boot space has shrunk considerably, from 745 litres to 625 litres. Folding the rear bench liberates 1540 litres, which is 138 litres down on the standard car's. Bear in mind that the Cayenne Coupé Turbo E-Hybrid's figures are lower again, at 600 litres and 1510 litres respectively.

The rest of the interior is largely carried over unchanged, with the same comprehensive dashboard and its various TFT displays. Plus there's now the option of a second infotainment screen that cleverly is invisible to the driver. It can show lap times or YouTube videos, depending on your passenger's mood.

Material fit and finish are first-rate. The cockpit oozes premium appeal, with the four-seat layout and lower roof helping to create a more bespoke and cosseting ambience. And if you want an even richer ambience, the GTS model provides it very effectively through plenty of tactile Alcantara trim and seats with additional lateral bolstering.

The car's old tunnel-mounted gear selector has been moved to the dashboard to free up some space for drinks holders and a wireless phone charger. Gear selection is now via a pull-down toggle to the left of the steering wheel. 

Up for reverse, down for neutral, hold down for drive and hold down longer for manual: it makes sense, and the little bar you push has a very Porsche-esque knurled material.

The Cayenne Coupé's engine range is broad enough to meet almost any requirement, save perhaps for those few customers who might still prefer a fast diesel. The pure-petrol V8s are torquey and mellifluous and can be ostentatious and vocal at high revs when working hard in range-topping models – and they always feel potent. The V6 PHEVs are slick, quiet, smooth and quite refined, and should meet the needs of those looking for a tax-efficient luxury SUV almost as well as any competitor. And if you're simply looking for the model that'll do it all and be refined and luxurious as well, a fairly stock Cayenne S is probably the way to go.

Then there's the top-of-the-range Turbo E-Hybrid PHEV, which really does do it all. Porsche claims that the Sport Chrono-equipped version, complete with GT Package, will crack 60mph from a standstill in 3.4sec. On the road, it feels blisteringly – almost antisocially – fast. Peak torque is still at a monstrously high 590lb ft and available anywhere between 2000rpm and 4500rpm, which is just where you need it for devastating point-to-point pace. In combination with the slick eight-speed automatic gearbox, which has an uncanny ability to second-guess your needs, the car makes mincemeat of the straights between corners, and very short work of  overtaking any cars that happen to be in your way.

Thankfully, you needn't spend all of the money or make it all the way up the showroom ladder to the top-of-the-line model to enjoy the best of what this car offers. The Cayenne's V8 engine is magnificent in any model it powers. It's potent, flexible and effusive – bombastic even, with the sports exhaust bellowing away. Yes, it has served in numerous Volkswagen Group products, but in the Cayenne S it seems to deal out its 443lb ft of torque like a croupier at the Casino de Monte Carlo. 

The E-Hybrid is powered by a 3.0-litre V6. On paper, this version looks just as fast as the V8 S, but unless you need to reduce your benefit-in-kind tax bills, it's not the one to go for if you're a really keen driver. It transitions from petrol to electric smoothly and its integration with the gearbox is sublime. When it’s at full chat, the 176bhp electric motor decadently covers the torque gaps of the combustion engine, and it feels like it’s doing a good enough impression of a V8. The problem is that the torque delivery is just not as broad as the V8's - so, at times, that feeling of strength under your toe isn't all that it could be.

While the Cayenne remains one of the firmer-riding and more connected-feeling cars in the luxury SUV set, and a natural choice for interested drivers, there remains quite a bit of bandwidth between the refinement and isolation levels of models at either extremes of its spectrum. A GTS with Porsche's sportier options fitted will feed back a lot more through its ride and steering than an E-Hybrid on air suspension, for example, which makes choosing just the right derivative for you the key to snagging the car at its best.

There's little doubt that the car is most impressive and best distinguished from rivals when sampled at its fastest, firmest and most dynamically engaging. Here, the slightly lower profile of the coupé body makes little difference to the sheer bulk that the car carries around. There's no denying that the Cayenne is a big, high-riding car, and could never have the purity of appeal of something so much smaller and lighter. But even so, the way that a Turbo E-Hybrid makes light of its 2.5-tonne kerb weight, controls its body and grips, feeds back and changes direction so freely and keenly makes it truly exceptional compared with so many duller and less agile performance SUV rivals.

A Cayenne GTS Coupé can be likewise as tactile, agile and entertaining. The car's special front axle makes for wonderfully informative steering, while chassis balance is responsive and direct, with outright throttle-on balance that merits comparison with rear-driven sports saloons. A Cayenne S, even, also goes above and beyond the handling appeal of most luxury SUVs, thanks to steering response and handling agility that can feel special even when you're not hurrying along.

Refinement and isolation levels are specific to the derivative in question. At the sportier end of the model spectrum, a Cayenne GTS or Turbo E-Hybrid Coupé can telegraph a reasonable amount of road noise through to the cabin, and filter out less than a typical luxury SUV might. But opt for a version of the car with a less performance-orientated agenda, smaller wheels and a bit more suspension travel (Cayenne S or E-Hybrid), and isolation levels are a lot closer to Mercedes, BMW and Range Rover levels. 

Whatever version you have, the car's adaptive dampers do a fine job of absorbing inputs and retaining ride suppleness, without letting body control run wild. Even at it firmest, the Cayenne Coupé never feels naggingly firm. It's not a car that wafts like some luxury SUVs can, but it generally breathes with the road, maintains composure, and soaks up nastier surfaces very impressively indeed.

As you would expect, running costs are on the steep side. Claimed fuel economy ranges from around 22mpg for the S right up to the 188mpg for the E-Hybrid. During our testing of the S, we saw figures as low as 13mpg during harder driving, but a day-to-day return of around 22mpg to 25mpg is likely.

The PHEVs can easily do sub-20mpg with no battery charge left in them too. But if you plug in at home and drive in a relaxed manner, they will be capable of close to three figures over an extended average.

Benefit-in-kind tax bands for the PHEVs are as low as 8% but go up to 37% for the V8s.

When Porsche introduced the Cayenne Coupé along with the rest of the third-generation model line-up towards the end of the last decade, we questioned whether it was an answer to a question nobody had asked. Wasn't a Porsche Cayenne a coupé in among boxier SUV rivals already? And what deeper sheen of desirability did it really need? Even today, they're lingering questions.

But Porsche's skilful derivative tinkering and life-cycle management has now made a clear place for the Cayenne Coupé within the wider Cayenne hierarchy. If you want the leanest, most dynamic and most eye-catching version of this car, you have to buy a Coupé. If you do, you'll be compromising a bit on passenger and cargo space, but not so much as to make you wonder where the regular car's utility value has gone - or even to flag to those who might have imagined that they were just buying 'the new Cayenne' that anything particular had changed.

It's clearly a mistake to over-rationalise the appeal of this car. The right Cayenne Coupé is a more appealing driver's car than the equivalent BMW X6, Maserati Grecale, Mercedes-AMG GLE 53 Coupé or Range Rover Sport, and it has a better finished interior than most.

Simply put, this is the Cayenne at its dynamic best: a 21st century luxury GT with eye-catching looks, good versatility and usability, and lots of exclusivity, which is fast, luxurious, and entertaining like little else short of an Aston Martin DBX or Ferrari Purosangue.