Compare the Porsche Boxster 2.5 Roadster - [1996] vs Mercedes 300 SL Gullwing Coupe - [1954]. 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 2.5 Roadster or the Mercedes 300 SL Gullwing Coupe. We'll leave it up to you to decide which is your favourite.