Compare the Jaguar XK R 4.2 V8 Supercharged - [2006] vs Audi A3 RS3 Sportback 2.5 Turbo - [2017]. 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 Jaguar XK R 4.2 V8 Supercharged or the Audi A3 RS3 Sportback 2.5 Turbo. We'll leave it up to you to decide which is your favourite.