The June Content Update (CU) should be available to everyone later today, typically around 10am Pacific Time. With it comes a long list of changes and updates. Yesterday saw the first edition of the "Forza Monthly" stream where they talked about what's coming in June (and also dropping news about what's coming in July, if you want to know, scroll to the bottom of this post). Doesn't seem like there's a YouTube video up yet, but you should be able to watch it on Twitch.
Here's a quick introduction to what's coming, you can read more details about this in the update announcement.
Hoonigan Car Pack
The Hoonigan car pack was previously only available to those who preordered the game. Now it'll become part of the car pass, so if you have that you'll get it too. Those who have neither can buy it as a regular DLC car pack.
Zakspeed Roush Mustang IMSA GT
The 1982 Ford #6 Zakspeed Roush Mustang IMSA GT will be given out for free to everyone. A Fox body-based version with around 530hp, fitting into the GT Racing Reborn division of cars.
Ford is the June spotlight manufacturer, by the way, so there will be rivals, leagues, and Forzathon events using and rewarding Ford cars.
Forzathons in FM7 will no longer be part of the Xbox achievements system and will instead be done internally by Turn 10. This is to allow for faster updates and more variety of events. To begin with, there will be weekly Forzathon events (like we've had in Horizon 3 for a long time).
Multiclass Multiplayer returns
They're bringing back the popular ABCS lobbies, yay! Scoring is improved, so it's on a per-class basis, and timing can be bucket-triggered so that for example the lowest class starts the race end timer.
Last month's update added test drive from a multiplayer lobby, this month's update adds the ability to tune as well!
Panning camera option
There's a new option in the camera effects menu that'll let you use a "panning" camera, which will make the photo look like it was taken from a standstill. This is so that the photo looks more like it would if taken by a photographer at the track.
Data output stream
There are now in-game settings for streaming telemetry data to another computer, allowing for data logging, or building your own motion sled if you fancy a little DIY project!
Yesterday's Forza Monthly stream featured a McLaren 720S in the studio, and they mentioned during the stream, perhaps not intentionally, that it's coming to the game in July. Yay!