Compare the Mercedes SLC 350 C107 - [1971] vs Audi A3 2.0 TDI S-tronic Quattro Sportback - [2016]. 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 Mercedes SLC 350 C107 or the Audi A3 2.0 TDI S-tronic Quattro Sportback. We'll leave it up to you to decide which is your favourite.