Two Convertibles with more similarities, such as the body structure, market segment, ground shadow size, height, and maximum occupancy, than differences, like the starting price, fuel economy, and horsepower. First of all, there is a $60,640 difference in the base MSRP. The 2017 Maserati GranTurismo Convertible has a higher starting price than the 2017 BMW 6 Series Convertible. And finally, the 2017 GranTurismo Convertible has bigger and thirstier engine; the 2017 6 Series Convertible gets 5.5 more mpg. Among similarities are the body structure, market segment, ground shadow size, height, and maximum occupancy.