2018 Mercedes-AMG GT C Roadster: The New In-your-face Roadster from the Three-pointed Star Published on March 29, 2017 in First Drives by Gabriel Gélinas Photo: Mercedes-AMG 2018 Mercedes-AMG GT C Roadster - 550 horsepower and 502 pound-feet of torque from the twin-turbo, 4.0-litre V8.