Compare the Porsche Boxster Spyder 3.8 981 - [2015] vs Alfa-Romeo 8C Competitzione - [2008]. 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 Porsche Boxster Spyder 3.8 981 or the Alfa-Romeo 8C Competitzione. We'll leave it up to you to decide which is your favourite.