Compare the Citroen XM 3.0 V6 - [1989] vs Audi Q7 4.2 TDi - [2007]. 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 Citroen XM 3.0 V6 or the Audi Q7 4.2 TDi. We'll leave it up to you to decide which is your favourite.