Two Convertibles with some similarities, but otherwise different in most aspects such as the model year, modifications, horsepower, fuel economy, height, and maximum occupancy. First of all, a bigger engine usually means less mpg. But the 2016 SL-Class SL 63 AMG has a more powerful engine and it gets 4 more mpg than the 2013 GranTurismo Convertible Sport. Also, the GranTurismo Convertible Sport is slightly taller than the SL-Class SL 63 AMG. In addition, the Maserati GranTurismo Convertible Sport seats two more passengers than the Mercedes-Benz SL-Class SL 63 AMG. Among similarities are the body structure, market segment, starting price, and ground shadow size.