EDIT: seems the mods were simply visual modifications from Forza 5, my bad
Those spoilers aren’t new to Forza. The S15’s spoiler is the Trials one, the Evo X is the Varis one, and the R-34 has the Top Secret Spoiler. They’re just like that in previous Forza games.
The wheels on the RX-7 were covered a few weeks ago. This is old news.