First post on this forum, so hi.
One customisation option that the Forza series loses to titles such as NFS Heat and The Crew 2 is the lack of headlight conversion from “pop up” type to “fixed” type.
Cars such as the RX7 that has pop up headlights but also often use as race cars have their lights replaced with fixed head lamps as a racing modification, for better aerodynamics.
For ingame I could see this as extra bumper options, or if need be, a body kit conversion that is otherwise identical, with the same choices of aero parts, with the only difference being the headlights.
I just think that would be a cool addition, especially for those (like myself) that like to make replica cars.