Two Convertibles with more similarities, such as the body structure, market segment, ground shadow size, height, and maximum occupancy, than differences, like the modifications, starting price, horsepower, and fuel economy. First of all, the 2016 BMW M6 Convertible is priced $143,700 lower compared to the base MSRP of the 2016 Bentley Continental GT Convertible Speed. Also, the 2016 Continental GT Convertible Speed has a more powerful engine than the 2016 M6 Convertible, and it gets 1 fewer mile on a gallon of fuel. Among similarities are the body structure, market segment, ground shadow size, height, and maximum occupancy.