Two Convertibles with some similarities, but otherwise different in most aspects such as the modifications, horsepower, fuel economy, ground shadow size, and maximum occupancy. First of all, a bigger engine usually means less mpg. But the 2017 Mercedes-Benz SL-Class SL 63 AMG has a more powerful engine and it gets 4 more mpg than the 2017 Maserati GranTurismo Convertible. Also, the body structure of 2017 GranTurismo Convertible is slightly larger than that of the 2017 SL-Class SL 63 AMG. In addition, the GranTurismo Convertible seats two more passengers than the SL-Class SL 63 AMG. Among similarities are the body structure, market segment, starting price, and height.