The Dinan modified BMW M5 E39 "M5 S2" is a 470 HP modified M5 with V8 that takes on the new BMW M5 E60 which is standard. They were giving it all they had.
http://video.google.com/videoplay?docid=-8489818365764452225&q=m5
http://video.google.com/videoplay?docid=-8489818365764452225&q=m5