Two articles on Forza website confirming the LCE and the BMW M5 F10.
http://forzamotorsport.net/en-us/LCE_ForzaMotorsport4/
http://forzamotorsport.net/en-us/BMW_M5_FM4/
Plus there is a design contest for you to create a custom livery for the M5 to be included into a future DLC pack.
http://forzamotorsport.net/en-us/FM4...ign_Challenge/