According to a recent report, Audi may bring the RS5 to the United States.

Even if details are limited "Automobile" says, based on an unnamed source that an American launch is "increasingly likely". The rumours are far from being official, but the posibility will be more than appreciated. RS5 comes with a 4.2-liter V8 with an 331KW output (450 PS) and 430 Nm of torque.
The "little engine" gives the posibility of acceleration from 0 to 100 KM only in 4.6 seconds while the top speed is limited to 250km/h through the electronic system. When you remove the speed limiter Audi RS5 may run with 280km/h. Anyway, the closer launch for US market for the RS5 seems to be the summer of 2011.