Compare the Vauxhall-Opel Insignia VXR OPC 2.8 V6 BiTurbo - [2010] vs Subaru Forester STi 2.5L Turbo - [2006]. 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 Vauxhall-Opel Insignia VXR OPC 2.8 V6 BiTurbo or the Subaru Forester STi 2.5L Turbo. We'll leave it up to you to decide which is your favourite.