Compare the Audi A3 S3 2.0 Turbo Convertible - [2014] vs Buick Regal GNX 3.8 V6 Turbo - [1987]. 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 Audi A3 S3 2.0 Turbo Convertible or the Buick Regal GNX 3.8 V6 Turbo. We'll leave it up to you to decide which is your favourite.