In Forza Horizon 1, the player would simply wear a white t-shirt and jeans when competing in street races and cruising around in the open world. When the player took part in any Horizon Festival event, they’d switch to a driving jacket and gloves, plus a helmet.
This was a really cool detail that brought some realism to a rather unrealistic game. Now that we have character customization, I think the player could have two outfits they customize themselves.
The casual outfit and the racing outfit. The racing outfit would be what they wear during Horizon events. Helmets, gloves, driving jacket. Since these are all still clothing items, they could have graphics and colors locked behind achievements to show other racer in MP how much they mean business.
You’d have the option to wear the racing gear on your casual outfit, but must have them equipped on your race outfit.