Confirmed:
Found on Reddit, note "Ultimate edition" as Assetto Corsa doesn't have an ultimate edition.
https://mobile.twitter.com/GAMEPreston/status/769085801460293632
https://www.reddit.com/r/xboxone/comments/4zqsbs/gamepreston_just_leaked_a_forza_horizon_3_demo/
Found on Reddit, note "Ultimate edition" as Assetto Corsa doesn't have an ultimate edition.
https://mobile.twitter.com/GAMEPreston/status/769085801460293632
https://www.reddit.com/r/xboxone/comments/4zqsbs/gamepreston_just_leaked_a_forza_horizon_3_demo/