Compare the Audi A5 S5 3.0 Quattro Cabriolet - [2009] vs BMW 5 Series 540d xDrive G30 - [2017]. Find out which car is the fastest, most powerful, lightest or has the biggest engine in our top trumps style comparison page. Find out which car has the highest top speed or is the fastest accelerating, is it the Audi A5 S5 3.0 Quattro Cabriolet or the BMW 5 Series 540d xDrive G30. We'll leave it up to you to decide which is your favourite.