Why? They're listed above in descending order of to-the-limit performance, but all are unreasonably fast and (mostly) uncompromisingly good when pushed hard.
The SLS AMG Black Series is unquestionably the track demon of the group, born and bred with that task in mind. A ferocious version of the 6.2-liter V-8 shared across the range gains upgraded internal parts and a race-like tune to extract 622 horsepower and an 8,000-rpm redline for Black Series duty. The result is a powerplant that just begs to be thrashed--and gives no indication that the thrashing pains it.
The SLS AMG GT, in both coupe and roadster forms, yields 583 horsepower, but slightly more torque, making it more tractable in day-to-day driving, but still a potent force when fully uncorked.
In all forms of the car, you'll get a seven-speed dual-clutch transmission, fitted with a mode-selector dial that offers Comfort, Sport, Sport+, and Manual modes. The Comfort mode is well-suited to around-town use, shifting smoothly and unobtrusively to keep coffee in its cup and the passenger from noticing a thing. Sport mode kicks things up a notch, adding a barking downshift now and then, while Sport+ awakens a computerized race driver, almost telepathically selecting the proper gear even under the most taxing conditions. Manual mode puts the driver in full control through the steering-wheel-mounted paddle shifters.
The combination of the smooth and quick transmission plus the strong standard 6.2-liter V-8 engine yields 0-60 mph times of 3.7 seconds for the SLS AMG GT Coupe and Roadster. The SLS AMG Black Series leverages its extra power and lighter-weight components for a 3.5-second run to the 60-mph mark. Due to the extra aerodynamic bits on the Black Series, however, it's a touch slower at top speed: 196 mph, versus the electronically limited 197-mph top speed of the standard models.
When it comes to dynamic response and handling, the SLS AMG GT doesn't disappoint. There's ample grip thanks to wide and grippy tires, though the overall balance tends toward a busy rear-end, wanting to step out at anything more than mild provocation from the throttle, particularly if you dare to engage Sport Handling mode (a single tap on the traction control button) or, even more bravely, to disable traction control altogether. At the absolute limits, the SLS AMG GT is a touch nervous, requiring a skilled driver to extract the best lap times. The SLS AMG Black Series tames this tail-happy tendency somewhat, despite the increased power, through even grippier tires, an electronically controlled rear differential, a slightly wider track, and improved suspension setup.
On the street, the Black Series' higher-performance tune is a bit more rough-and-tumble, though even the base SLS AMG GT models are firm and frisky over broken or rough-surfaced pavement.
All models offer the AMG Performance Media system that essentially puts an LCD face to your driving heroics. It translates lateral grip, acceleration, engine data and lap times into an ever-changing display that doubles as the car's navigation system when you blip out of AMG mode.