Earlier today gameplay footage got out, featuring several several of the LEGO cars roaming the environment with throw backs to several themes on top of Speed Champions, that should be exciting to a lot of folks here including Alien Conquest and Pirates:
Cars race full speed in the released gameplay.
Also of note a description of what the expansion will include got out, featuring many interesting details, including additional gameplay details, information about what cars will be in game, and the world:
Explore a LEGO Themed World – In an all-new valley filed with LEGO brick structures, find out how fast you can go around the Falcon Speedway and how far you can jump in the fun-filled Super Mega Awesome Adventure Stunt Park. Experience how seasons change a LEGO city, airport, UFO crash site, pirate cove and more.
Discover LEGO Brick Challenges – Embark on a new LEGO Brick Challenge Campaign that rewards free exploration and build a Master Builder’s House as your collection grows. You will also encounter other new gameplay challenges such as LEGO Speed Ramps and Destruction challenges.
Become a LEGO Speed Champion – Collect and race new LEGO Speed Champions cars, such as the McLaren Senna, Ferrari F40 Competizione and the 1967 Mini Cooper S Rally, against real world cars that utilize the Forza racing franchise’s renowned physics and handling. You can also work to become a LEGO Speed Champion hero in a grand finale race on an epic LEGO Goliath route.
We also got some interesting new promotional render images, featuring "normal" and LEGO cars alongside each other:
As we didn't have this information at the time the first article was written, I'll also note the game will cost 19.99$ in US currency and be included free in some versions of Forza Horizon 4:
Forza Horizon 4 LEGO Speed Champions will cost $19.99 and is included at no additional cost for players who own the Forza Horizon 4 Ultimate Edition, the Forza Horizon 4 Expansions Bundle or the Forza Horizon 4 Ultimate Add-Ons Bundle. Xbox Game Pass members have access to the standard edition of Forza Horizon 4 and are eligible for 10% off a standalone purchase or 10% off the Forza Horizon 4 Ultimate Add-Ons Bundle.