Who cares if faster or slower either one? Whomever buys an Audi or a BMW or any other car out there is because he likes it better than the other choice he/she had. It is not about who's faster, there will ALWAYS be a faster car out there, and comparing one to the other on the basis of top speed or acceleration or handling on a track or anywere else to own one is for kids playing 'my dad is taller than yours' or 'my dad is stronger than yours' (or for teens measuring their d..k lenght) This ain't no pissing contest. Tell your friend that the RS4 may well be faster than the M5, but I for one, as an M5 owner won't trade for the Audi + plenty of $ on top. I'd have bought one if I wanted to, so WHO CARES? btw: mine is 10" long...hahahahaha Marcelo