Compare the Alfa-Romeo 156 2.4 JTD - [2003] vs Porsche Panamera 3.0 V6 Turbo Diesel - [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 Alfa-Romeo 156 2.4 JTD or the Porsche Panamera 3.0 V6 Turbo Diesel. We'll leave it up to you to decide which is your favourite.