https://www.gamespot.com/articles/forza-horizon-4-release-date-confirmed-at-e3-2018/1100-6459604/

Forza Horizon 4 will launch on October 2, Microsoft announced today during the Xbox E3 2018 briefing. The racing game sequel from Playground Games will also be available to Xbox Game Pass subscribers at launch for free. All Microsoft Studios games are free at launch with Game Pass.

Forza Horizon 4 is set in Great Britain; the previous Forza Horizon 3 took place in Australia. A lot of new features were shown in the announcement trailer, including dynamic weather, different seasons, and shared-world multiplayer.