Two Convertibles with some similarities, but otherwise different in most aspects such as the starting price, fuel economy, horsepower, and ground shadow size. First of all, the 2016 BMW M4 Convertible is priced $71,540 lower compared to the base MSRP of the 2016 Maserati GranTurismo Convertible. Also, the 2016 GranTurismo Convertible has a more powerful engine than the 2016 M4 Convertible, and it gets 5 fewer miles on a gallon of fuel. And finally, the M4 Convertible has a slightly smaller body than the GranTurismo Convertible. Among similarities are the body structure, market segment, height, and maximum occupancy.