Thats a matter of taste. At least the Audis are faster.  
Faster then camaro 
Faster then camaro 
Faster then camaro 
Much faster then camaro 
Faster again, this is getting boring 
  hp/weight 
S4 340/3870 
S6 420/3800 
S8 450/4200 
RS6 480/3900 
RS4 420/3700 
Camaro 400/3800+ 
If the camaro is anything like other retro styled steel beasts, it'll be over 4000lbs, and by no small margin. It may beat the standard S4 in a roll race, depending on the retro drag coef. But the S4 will launch harder. The 500 hp flavor of the LS2 gets the 3100lb Z06 to 60 in 3.4 seconds, add 900-1000 lbs and you'll pick up 2 seconds if not more. The Audis 0-60: 
s4 5.4 
s6 5.1 
s8 5.0 
rs4 4.7 
rs6 4.0   
So, by the numbers, the S4 vs the Camaro may be a close race, if Chevy is lucky, untill its time to turn.  Also consider the fact that the audi's will probably get faster by 2009.