With GM and Ford coming out with 550/650hp cars for cheaper.. those ARE now being cross shopped with the M3/Audi/MB brand because of the price-to-fun ratio.. Remember the '12 Mustang GT and the E92 M3?
The new RS car is going to have the RS5 motor.. and the new M3 has the turbo'd 6 coming for it.
While it may handle better than the US variants, most people don't track their cars and love ACCELERATION it seems. If you want a track rat, you get an Elise..
The new camaro/mustang's are already on par with these european sports car on the track.. besides the obvious interior/exterior.. Why wouldn't anyone want one since they're so much cheaper?
When the M3 with the turbo hits 550hp, the ZL1/GT500 will be at 700whp...