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 - The soft top can be lowered or raised in about 11 seconds, even if the car is in motion at speeds below 50 km/h.