Two Convertibles with some similarities, but otherwise different in most aspects such as the starting price, horsepower, fuel economy, ground shadow size, height, and maximum occupancy. First of all, there is a notable difference in the starting price of the 2015 BMW Z4, which is $12,150 less than the base MSRP of the 2016 Audi S5 Convertible. Also, the 2016 S5 Convertible has a more powerful engine than the 2015 Z4, and it gets 2 fewer miles on a gallon of fuel. In addition, the S5 Convertible body is slightly larger than the Z4, and in addition to that, it's also taller. And finally, there is a difference in the number of passengers; the Audi S5 Convertible seats two more the BMW Z4. Among similarities are the body structure and market segment.