Compare the Audi A6 3.0 TDI BiTurbo Avant Tiptronic - [2016] vs BMW 5 Series 540i M-Sport E39 - [2002]. 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 A6 3.0 TDI BiTurbo Avant Tiptronic or the BMW 5 Series 540i M-Sport E39. We'll leave it up to you to decide which is your favourite.