I don’t know if this is something that is limited by licensing, but one thing I would love to see happen at some point (whether in FH5 or future Forza games), is making body kits compatible between cars that are identical.
For example - the Liberty Walk kit exists in the game for the base F82 BMW M4, but it does not exist for the M4 GTS, even though they’re both basically identical exterior wise other than some very minor differences (taillights, stock front lip etc)
Or the 3 R35 GTRs in the game, the Black Edition has the LW kit, the 2017 has no kit, and the NISMO has another different kit, would be cool if the 2 kits that currently exists for the R35 can be applied to all models of the R35 GTR, and not just one specific model