540 are generally boring cars in term of performance. Tried the E39 & its too linear. No fun. Tried the RS4 here & it flies in stock form. Open the hood & you are welcomed by all the carbon fiber. YUM YUM!
New RS4 will probably loss out to the E90M3. Rs4 420bhp vs M3 450 or so bhp (From reliable source) & both NA. But with the turbos, it's a different beast with a little tuning.