Compare the Cadillac CTS -V 6.2 V8 Auto - [2009] vs Porsche 911 Carrera GTS Cabriolet PDK - [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 Cadillac CTS -V 6.2 V8 Auto or the Porsche 911 Carrera GTS Cabriolet PDK. We'll leave it up to you to decide which is your favourite.