Vacuum your car seats thoroughly and use a steam cleaner if necessary to remove grime or stains. Leave steam-cleaned seats to fully dry before painting.
Tape off the surrounding areas with masking tape and plastic. Don't fret too much about getting paint on other surfaces as the spray cans emit a narrow spread of spray and the paint is easily wiped away from hard surfaces. Cardboard can also be used to block off areas while painting.
Spray in slow, even, back-and-forth motions, holding the can 5 to 8 inches from the surface. Be sure to get into grooves and crevices.
Stop periodically to massage the paint into the upholstery with your hand. Upholstery paint is easily washed from your hands. Have a wet rag available to clean any paint that gets onto unwanted surfaces. Clean these splatters as they happen.
Leave the paint to air dry overnight. Add a second coat if necessary to enrich or even out the color.