The engine displacement of BMW 4 Series convertible is not higher than that of Audi A5 convertible. The maximum engine displacement of Audi A5 convertible is 4.2L, while the highest engine displacement of BMW 4 Series convertible is 3.0T.

The transmission used in cars is different. BMW 4 Series cars are equipped with an 8-speed automatic transmission, while Audi A5 convertible offers multiple transmission options, including 6-speed automatic, 7-speed dual clutch, 8-speed CVT automatic, and CVT stepless transmission (simulating 8-speed). So, Audi A5 convertible has more transmission choices than BMW 4 Series.

The car body dimensions are different. The length and width of Audi A5 convertible are longer and wider than those of BMW 4 Series convertible, but the car body height is lower than that of BMW 4 Series convertible. The dimensions of Audi A5 are 4760×1843×1342, and the dimensions of BMW 4 Series are 4670×1825×1408.