Compare the Saab 9-3 Viggen 2.3L Turbo - [2001] vs BMW Z4 sDrive28i E89 - [2011]. 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 Saab 9-3 Viggen 2.3L Turbo or the BMW Z4 sDrive28i E89. We'll leave it up to you to decide which is your favourite.