Vinyl Paint

The problem isn't what vinyl paint to use.........but what will hold up on the seats, and not wear off, cause seats probably get a lot more sliding action than other vinyl parts.
Good prepaint prep is another critical factor. Use all matching namebrand paints. Also clean, clean, clean, useing vinyl prep cleaners/greease, and wax removers, and adhesion promoters.
SEM, and Krylon are two that I have used.
I have never done a set of seats from white to a darker color. I think that will be tough.
I would talk to some one who does upholstery, and see if there is a dye available (like leather dye, for leather) that will penetrat beneath the surface, and actually change the color, instead of just coating it, which is what vinyl paint does.
Dave