Compare the Audi A5 S5 3.0 Quattro Cabriolet - [2009] vs Cadillac STS 4.6 V8 Sport Luxury - [2005]. 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 Cadillac STS 4.6 V8 Sport Luxury. We'll leave it up to you to decide which is your favourite.