Here some new Infos about the new M5 and M6 from the German Magazine "AutoMotorundSport":

They will get a new V10-40V-engine with 550 hp at 9000rpm.

More Infos:

http://www.autouniversum.de/AU/DE/de/homepage.jhtml?navi_param=news_bericht&repId=%2FAU%2FDE%2Fde%2Fcontentrepositories%2Fde_d e_newsTuningAccessoriesRepositoryXML%2FXML%2FNews2 737.xml&overviewPage=news_ueberblick&news_newsart=newsTuningAccessories