Compare the Audi A3 2.0tdi Quattro S-Line - [2008] vs Ford Fiesta ST - [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 A3 2.0tdi Quattro S-Line or the Ford Fiesta ST. We'll leave it up to you to decide which is your favourite.