Some Info About Painting With Enamel.
Back in 2000 I dyed the entire interior of my Barracuda from Blue to Black with SEM Landau Black vinyl dye with the exception of the headliner and carpet. About a year latter I was given a new front seat that that didn't have any broken springs and had perfect white upholstery. I dyed it black. It wasn't until when the stitching started to separate that I purchased new covers for the seats, door panels, visors, arm rests upper and lower dash pads, dash, kick panels, etc are still dyed items. In that period of time I put approximately 45,000 miles on the car and currently have accumulated 65,000 miles. The SEM dye has held up fantastically and the only areas that it has required any touch up is/was the piping on the edge of the seat where I slide my butt in an out and everyother year or so the drivers side kick panel.
NOTE: I tried the Duplicolor black but it does not look as natural as the SEM Landau Black, too much gloss with the Duplicolor.
Regarding enamel paints for automotive use: They are rarely used to day because they are not as forgiving or as durable as the current standard, acrylic urethanes. The urethanes spray as easily as lacquer but will give a gloss equal to or better than an enamel. They dry and are ready for color sanding in 24 hours if cured at room temp or in a couple of hours if cured at an elevated temp. Plus spot repairs are much easier with urethanes. The down side is the cost and they do present more of a health hazard so proper PPE is required.
The urethane materials are available at your local autobody supply house in primer and basic colors like black, white, silver, red, etc. I keep aerosol cans of DuPont self etching primer, primer surfacer and SEM Weld Through Primer for small quick projects. Where those small projects require a matching top coat I use either a hobby air brush with canned propellant or for bigger items I will pull out my jam gun.