Actually, in regards to horsepower, the GT S Roadster's almost perfectly in the middle. Its twin-turbocharged 4.0-liter V8 makes 515 horsepower, which is 46 more than the GT, and 35 less than the GT C. Torque is much closer to the GT C, though, at 494 pound-feet. That's just 8 shy of the higher-end sibling. Power still goes through a 7-speed dual-clutch transmission to the rear wheels. In the 0-60 mph sprint, Mercedes claims a time of 3.7 seconds, just one tenth off of the GT C.
The GT S Roadster gets a number of other performance upgrades over the standard GT, too. It gets adaptive suspension, an electronically-controlled limited slip differential, variable-sound exhaust, 10-mm wider front tires, one-inch taller rear wheels, and a fifth driving mode called "RACE" (Mercedes-AMG's capitalization, not mine). All of these features are also found on the GT C. One missing feature that the GT C adds is the excellent rear-wheel steering that makes the car noticeably more nimble.
Visually, the GT S looks like a normal GT. This means it features the narrow body not used on the GT C and GT R. And the only major differentiator between the GT S and GT are the wheels. The interiors are effectively the same, too.
This new mid-level AMG GT S Roadster will be available later this year. Pricing hasn't been announced yet, but we expect it to fit right between the GT and GT C in price. The GT starts at around $125,000, and the GT C starts at a bit under $160,000. Official pricing details will come closer to the on-sale date.