Forza Horizon 4 is one of the Xbox/PC exclusive game that is expected to be revealed by Microsoft at their Xbox E3 2018 press briefing. According to the multiple rumors on the internet, Forza Horizon 4 is currently in development at Playground Games and is scheduled to launch in second half of 2018, and it will be set in Japan.
Today, the first batch of Forza Horizon 4 concept art has been leaked, and the first thing that it confirms is JAPAN setting. You can take a look at them below.
Back in January 2018, Brazilian Classification Rating Board listed Forza Horizon 4 with 2018 as the release date. No other details are mentioned in the listing. This is definitely a sort of confirmation that the game will be released in 2018 as a playable version must have been made available for testing considering that it has made it to the rating phase.