Compare the BMW X6 M 4.4 V8 Turbo F86 - [2017] vs Audi A3 RS3 2.5 Turbo - [2018]. 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 BMW X6 M 4.4 V8 Turbo F86 or the Audi A3 RS3 2.5 Turbo. We'll leave it up to you to decide which is your favourite.