For the past 50 years, the Porsche 911 has carved out a sizeable niche for itself, managing to be highly desirable and yet selling in higher numbers than any other comparable car in the price bracket. However, to understand Porsche’s dominance you need to realise that not only has the badge been around for a very, very long time, but the 911 range is vast, too — there’s almost something for everyone.

The most expensive version is about twice the price of the cheapest, there are two-door Coupé and Cabriolet body styles and a third, the Targa with its cool folding hard-top (all with a 2+2 cabin that ostensibly seats four), buyers choose from manual or automatic transmissions and rear- or all-wheel drive. And topping all that off are the more extreme 911 GT2, GT3, RS and Turbo derivatives (not to mention the unicorn-like 911 R), some of which are effectively supercars.

Mercedes, or specifically its Mercedes-AMG high-performance division, wants to change all that, which is why it launched its own alternative in 2014, called simply the AMG GT. That car was initially offered as solely as a two-seat coupé and in two states of tune, the GT and GT S, while the range was bolstered earlier this year by the arrival of the hardcore GT R with trick aerodynamics, more power, a sophisticated rear-wheel steering system and variable traction control straight out of AMG’s racing cars.

Next up, the AMG GT will be offered in two-seat, open-topped Roadster guise, which is seen to be crucial for AMG’s biggest market, America, even if we prefer not to have our heads fried here in the UAE (despite that, there’s plenty of demand in the cities for open cars, as they help their owners be seen…). And being seen is what the AMG Roadster is, it could be suggested, all about.

The arrival of the Roadster has been timed to coincide with a raft of changes for the Mercedes-AMG GT range as a whole, so it features the fabulously aggressive-looking ‘Panamericana’ radiator grille that debuted on that mental AMG GT R, for a start, plus other niceties such as active aerodynamics up front. The Roadster’s fabric roof can be ordered in red, beige or black and it opens or closes in about 11 seconds, even on the move at speeds of up to 50kph.

With the roof folded away, the side windows up and the tiny little wind deflector in place, the GT Roadster isn’t as blowy as you might expect. That’s because the seats are mounted low down and there’s a high transmission tunnel, making occupants feel cocooned. And while the interior shares plenty with normal Mercedes-Benz cars, there’s loads of bespoke switchgear and detailing to ensure the GT buyer feels special, such as all the drive settings’ switches on that huge centre console.

It’s also worth splashing out on the fantastic AMG Performance seats (so long as you’re not too wide of frame yourself), as they come with a lot of adjustment and they really hold you in place through the corners. They can also be fitted with a highly effective neck-heating system for those late-night drives through the desert, and even climate control.

And there’s no doubt you’ll want to have the roof down as often as possible, as it allows unobstructed aural access to the sounds coming from the four exhausts, and in this car, those sounds are reason enough to buy it.

Under the bonnet of all versions of the GT is a twin-turbocharged 4.0-litre V8 engine and even the lowliest model has 476bhp and 630Nm of torque at its disposal, plus a variable exhaust system that does its best to keep the noise at bay in its Comfort setting, while allowing the engine full voice in its Sport mode. And it really is something special to behold. A deep rumble at low speeds develops into a meaty V8 baritone higher up the rev range and it seems to cackle in an evil manner on the over-run as you leave off the throttle.

And there’s no doubt you’ll want to have the roof down as often as possible…

The new GT C version sits between the GT S (522bhp/650Nm) and the rip-snorting GT R (585bhp/700Nm) with outputs of 557bhp and 680Nm of torque. What’s more, that chunky torque figure is a mere toe-flex away all the way from 1,900rpm to 5,750rpm. That, it is no coincidence, is where peak power kicks in, and it remains at the full level for another 1,000rpm. By which stage it’s highly likely you’ll be changing up a gear and wondering how long your driving licence is going to last…

All that power goes through a slick seven-speed automatic transmission to the rear wheels. Some may lament the lack of a manual gearbox option, but thankfully the auto is a peach, with various modes of operation including a fully manual setting where you control it via tactile gearshift paddles mounted behind the steering wheel. Response to these is rapid and down-changes are accompanied by evocative throttle blips.

Those of a nervous disposition may worry about all that power going through the rear wheels, but Mercedes has done a phenomenal job with this car’s chassis. It’s not too heavy, has a low centre of gravity, a very well-judged ESP stability control system and simply huge depths of mechanical grip to lean on. Body control is exemplary through rapid direction changes and while you pay for that in terms of a firm ride, the GT Roadster is perfectly capable of long journeys without requiring a visit to the chiropractor afterwards, because of its variable damping system.

Push that chassis to its limits and the AMG GT doesn’t bite back, either. In fact, it’s remarkably progressive, making it a ‘friendly’ car to drive quickly on an interesting road or racetrack, while still rewarding those who really know what they’re doing. And another thing, while open-topped versions of existing sports coupés are often tarred with a brush marked ‘softer and for posing only’, the AMG GT Roadster is anything but. The weight increase due to structure stiffening has been minimal and yet it feels just as rigid as the coupé and certainly just as much fun to drive.

That’s especially the case in the GT C variant. It’s clearly targeted at vanquishing the evergreen Porsche 911 Turbo, which is stupendously fast and competent in all conditions. Sure, the 911 comes with four-wheel drive, but the AMG GT C is much more exciting to drive, far more interesting to look at and it sounds simply sublime. Suddenly, the Porsche 911 is not the default choice in this rarefied atmosphere it used to be.