Compare the Subaru Forester STi tS 2.5L Turbo - [2012] vs BMW 5 Series 54.d xDrive Touring G31 - [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 Subaru Forester STi tS 2.5L Turbo or the BMW 5 Series 54.d xDrive Touring G31. We'll leave it up to you to decide which is your favourite.