Barb---Things may have changed a bit in the last 30 years, but if you are using a one step paint, not base clear, it will probably be much the same as acrylic enamel. I painted about a thousand cars with that during the seventies and eighties, and it took a full gallon of mixed paint. My standard was 3 quarts of paint, one quart of reducer, and a few drops of "smoothie" (fish eye eliminator). --I tried to avoid using a hardner if I was using a standard enamel, because it added to the cost of the materials. with acrylic enamel, you had no choice---you had to add a hardner, but the overall quantity of paint stayed the same---one full gallon of mixed paint. that would allow two full wet coats of paint, and a third coat "misted" on at a higher pressure to make metallic coats lie down and blend better.---brian