As with any AMG model, it's the engine that defines this car, a 4.0-litre biturbo V8 offering 476hp in the base 'GT' model, 522hp in the 'S' model, 557hp in the 'GT C' variant and 585hp in the top GT R model. In all its forms, it's a glorious-sounding powerplant with a lavishly intoxicating soundtrack that will never let up. The GT R variant gets to 62mph in just 5.3s en route to 197mph if you find yourself a track or an empty autobahn. All this frantic potential is harnessed by an 'AMG SPEEDSHIFT DCT' 7-speed paddleshift auto gearbox with transmission toys that include a 'RACE START' launch control feature and software that blips the throttle on downshifts to the evocative accompaniment of popping and banging from the switchable AMG Performance exhaust system.
The exhaust note is one of the parameters influenced by the various settings of the car's 'AMG DYNAMIC SELECT' driving mode system, this being one of those set-ups that can alter throttle response, steering feel, gearshift timings and stability control thresholds to suit the way you want to drive. On the 'GT C' and 'GT R' variants, the set-up controls the damping too, courtesy of an 'AMG RIDE CONTROL' adaptive damping system we think you'll need to keep this car in check at speed over bumpier surfaces. It's on roads like these that you'll also appreciate this car's rear axle differential lock, a feature that's electronically-controlled in these top models for quicker response.
Any supercar must be an eye-catching thing. The old SLS Roadster certainly was and, like that car, this GT Roadster model makes quite an impression at first glance. It's shorter and narrower than its predecessor, with aesthetic aggression that's ramped up several more degrees. Get one of these in your mirrors and you'd move over. Quickly. The fabric roof gives the GT model's profile a subtly different line when raised, but the look is still handsome and the hood can be lowered in just 11 seconds to fold neatly away beneath the rear deck.
Take a seat behind the wheel and the SLS underpinnings are betrayed by the way the designers have had to retain that car's huge over-sized central transmission tunnel, which comes in a choice of chromed, high-gloss or, as in this case, carbon finishes. In a nod to the V8 engine up-front, it features eight 'AMG DRIVE UNIT' control buttons laid out in a V-formation. The AMG performance front seats are optionally available with the AIRSCARF neck-level heating system, which makes open-air driving enjoyable even in low outside temperatures. The air vent is seamlessly integrated into the seat's head restraint area. To meet the individual preferences of customers, the temperature of the warm airflow can be set in three stages.
Expect to pay a premium of around £11,500 for this Roadster model over the standard Mercedes-AMG coupe. This means that even before you've allowed for a few well-chosen extras, you'll need to work with a budget of around £116,000 for the base GT Roadster, about £130,000 for the GT S version, around £145,000 for the more potent GT C model and around £179,000 for the top GT R.
All models of course are very well equipped. Whichever one you choose, you can expect to find LED High Performance headlamps and heated sports seats trimmed with nappa leather and featuring electric adjustment and memory settings. Plus there's THERMATONIC' climate control, an electrically extending rear aerofoil, an anti-theft protection package and an 'AMG Performance' exhaust that can be made louder by opening flaps inside the system at the touch of a button on the centre console. You also get an 8.4-inch centre dash screen via which you operate the standard COMAND Online' system, which includes a DAB radio, a CD and DVD player, satellite navigation with 3D mapping and 'Live Traffic Information. The system will access various Mercedes apps, has connections for USB sticks and SD cards and includes integrated wifi with links to Facebook, Google Maps and weather updates.
You'd expect this Mercedes-AMG GT Roadster to be more efficient than its SLS predecessor. It's around 100kgs lighter, with an engine 2.2-litres smaller and a power output that's up to 91bhp down on its gull-winged predecessor. Nevertheless, you might still be surprised by just how much the engineers from Affalterbach have achieved here, given that they were tasked with creating an open-topped supercar that would be just as quick as the one it replaced.
Some stats will help illustrate the point. The kind of returns the old SLS Roadster delivered - around 20mpg on the combined cycle and well over 310g/km of CO2 - remain better than those you'd get from a Maserati Gran Cabrio of today and these kinds of figures remain close to the sort of readings you'd also still find with some of today's Ferraris, Lamborghinis and Aston Martins. Even the supposedly more efficient powerplants you get in the latest McLarens or Audi R8s still put out CO2 figures in the 260 to 270g/km bracket and can't crack 25mpg on the combined cycle.
It's possible to share Mercedes-AMG's quiet satisfaction then, in readings that see the standard version of this GT Roadster delivering figures that aren't really very much different from those of the C 63 Cabriolet model that shares its same 4.0-litre V8 biturbo engine. Even the top GT R manages a combined cycle WLTP economy range between 16.9 and 22.6mpg, plus an NEDC-rated CO2 emissions showing of 294g/km.
The second Roadster designed and built by Mercedes' AMG division is very different from the first. The old SLS drop-top could be both supercar and a Continental cruiser, but with this AMG GT, you sense from the beginning a refining of priorities. It's raucous, raw and uncompromising in its driver focus. As one writer put it, 'it's Merc's Mustang'.
You'll either like that or you won't. If you don't, your Mercedes sales person will walk you gently over to the other side of the showroom where you can take your seat in the brand's more laid back SL roadster, the Benz that's freed up this car to be the road racer it is. The SL's a very nice machine, but it can't provide the memorable, white-knuckle, thrilling experience that it's possible to enjoy in a GT Roadster.
It's the kind of car that enthusiasts will still be talking about a century from now. There isn't anything more than that that needs to be said.