It was previously understood that Forza Motorsport 5 would need to be online to download an update prior to playing the game, but Turn 10 Studios head Dan Greenawalt has since spoke with IGN about the Xbox One title and said that this isn’t the case:
“In the beginning of the game, the player will be racing against Drivatars that are contained on the disc and were trained by the [Turn 10 development] team. While playing, the player will be asked to connect to Live in order to download a completely fresh set of player-created Drivatar opponents – it’s not a lot of data, but the download contains enough Drivatars to cover all difficulty settings. Connecting will also download new content – but the vast majority of the launch content is contained on the disc. This download is simply additional cars and tracks. The gameplay is not blocked while downloading the additional content; it’s done in the background just like disc install.”
The majority of the game’s content will be included on the disc and Xbone owners will be able to play it from the offing. However, some areas in career mode appear to require the update that will be available on day one.