Porsche makes such an extraordinary variety of 911s that even among convertibles there are eight variants.

They start with a rear-wheel drive Carrera Cabriolet at $229,900 and climax with the all-wheel drive Turbo S Cabriolet at $466,900.

Among the upper tiers are GTS models, which are enhanced versions of the Carrera S Cabriolet with special features and a high level of trim and equipment.

To anyone with a fondness for the model the GTS presses all the right buttons

The premium for the GTS badge over an equivalent model ranges from $22,500 to almost $24,000. But it would cost much more to equip a standard car in the same way and many of the extras — more power, for example — are unavailable without the badge.

Design

The differences between 911s can be too subtle for some, but to anyone with a fondness for the model the GTS presses all the right buttons.

Chief among them is its "wide body" shape, which flares the rear wheel arches by about 4cm and sets the wheels farther apart.

The wheels themselves are 20-inch centre-lock black forged alloys borrowed from the 911 Turbo S. Detailing in black also marks out the sideskirts, exhausts, rear grille and apron while the headlight covers are smoked. It stands out from a regular car.

In place, the fabric roof conceals its ribs effectively for a smooth cabin contour that flows into the bodywork in one continuous line.

That's OK. But with the roof down, the tall rear needed to fit it all is more obvious and it makes the car look a bit humpbacked.

Either way, 911 cabrios have a different silhouette from coupes, and to most eyes never look quite as good.

Interior 

In a convertible, an interior must be fit to display and while the GTS cabin is as familiar as every other 911 cabin, there's enough to make it feel a bit special.

Non-premium materials have been banished and replaced with lots of contrast-stitched leather, Alcantara and carbon fibre trim. The Alcantara-covered steering wheel is especially pleasing while the sports seats, as usual in a Porsche, are excellent.

With the roof in place, the thick fabric does a good job of keeping out road noise and you can almost forget you're in a convertible.

Even by 911 standards, the rear seats are useless

Roof down, a power-operated wind-blocker can be deployed behind the front seats to prevent the cabin becoming blustery. The roof operates quickly enough and, crucially, can be closed on the move at speeds of at least 50km/h.

There are a couple of niggles. Over-the-shoulder vision is heavily compromised by the width of the roof and the wing mirrors offer a very narrow field of vision, insufficient to cover a blind spot with confidence.

Even by 911 standards, the rear seats are useless except for infants and luggage.

And when will car makers agree to make electronic park brakes all function the same way? Push or pull for on? Those in 911s operate counter-intuitively.

Engine / Transmissions

The GTS gets the same 3.8-litre horizontal six-cylinder engine as the Carrera S, but reworked to extract 22kW more power, with 316kW at 7500rpm.

For this sort of money many rivals offer V8s, but Porsche's 3.8-litre horizontal six is an exceptionally sweet engine. It's creamily responsive in a way no turbocharged unit can be and, with the sports exhaust button pressed, has an engaging repertoire of whirrups and crackles.

The double-clutch automatic transmission is also one of the best you can buy

Porsche's seven-speed manual is standard in this car, but most buyers will choose the two-pedal option and miss out on an exceptional gearbox.

However, the double-clutch automatic transmission is also one of the best you can buy, with rapid and timely shifts. Unlike traditional torque converter autos, it's quicker and more economical than the manual unit. It shaves 0.4s off the zero to 100km/h time (for 4.2s) and saves 0.8 litres of fuel per 100km (for 8.9l/100km).

They are impressive figures that none of its rival 2+2 drop-top V8s can match.

One reason for its relatively good fuel economy figure, though, is a stop-start system that's as annoying as any.

Sampled overseas, the GTS with all-wheel drive is a $36,600 premium over the rear-drive model. Unless you really do spend all winter in Falls Creek, that looks steep; the all-wheel drive is no quicker but thirstier and heavier than the rear-drive car.

Driving

Included with the GTS are many of Porsche's best dynamic options that would be additional on a standard car.

These include active dampers with 10mm lowered ride height and torque vectoring with a rear differential lock. This system selectively brakes rear wheels to assist rotating the car around a corner.

The rear differential, along with the wider rear track and tyres on the GTS, also help get power down on exit.

Everything seems bulletproof

Most convertibles feel compromised by the loss of rigidity that goes with chopping off a roof, but the GTS loses little.

Everything seems bulletproof and almost as solid as the coupe, with similar levels of composure and steering precision. The brakes are fantastic, as you would expect in a Porsche.

With its rear-mounted engine, a 911 promises a particular sort of driving experience and the GTS Convertible certainly delivers on that promise.

Safety

The GTS Convertible — and for that matter, any 911 — has yet to be tested by independent bodies such as NCAP, but Porsche has been perfecting the recipe for half a century.

There's no shortage of airbags, although anyone looking for autonomous braking, lane alert and other systems that are becoming ubiquitous on family cars will be disappointed.

To most Porsche buyers, they would be out of place in a sports car in any case.

Aside from the features already mentioned, the GTS includes Porsche's Sport Chrono package. This brings launch control, lap timing capability and a Sport Plus button that sharpens the steering and suspension while raising the intervention threshold for stability control.

If you want a 911 Convertible, then the GTS is right in the sweet spot

The GTS also gets active engine mounts, which prevent unwanted movement of the unit during cornering, and "intelligent" dynamic lights.