Color changing interior. Dying black vs. buying new.

Prepping is key, degrease thoroughly and use an adhesion promoter. Most auto paint jobbers can mix vinyl dye in any color or sheen you want. Some can even load it into a spray can. I can't say how a high wear item like a seat bottom would hold up, but have dyed dashes, door panels, even vinyl tops with good success. You don't want to pile the dye on, less is more.