Two Convertibles with more similarities, such as the body structure, market segment, starting price, ground shadow size, height, and maximum occupancy, than differences, like the horsepower and fuel economy. And finally, the 2016 BMW 4 Series Convertible has a more powerful engine than the 2015 Audi A5 Convertible, but it gets 2 more miles on a gallon of fuel. Among similarities are the body structure, market segment, starting price, ground shadow size, height, and maximum occupancy.