I test drove a new '09 STI... DEFINITELY felt slower than my 135i Step. It has a cheap interior, but it's still a nice car (and probably better for the track after mods).
For example... check out this STI...
http://video.kenblockracing.com/flash/small_player/preloader.swf?vendor_id=204&media_i d=9183&bgcolor=FFFFFF&autoplay=0