Small to medium-sized cars require about 1 gallon of primer, 3 gallons of topcoat, and between 2 and 3 gallons of clear coat, according to Popular Mechanics. Large cars require 1 1/2 gallons of primer, 4 gallons of topcoat, and between 3 and 4 gallons of clear coat.
Professionals may use less paint, but it is better to have extra paint than not enough. Auto paint shops can usually match the original color of a car as long as they have the color code, which is found on the vehicle’s compliance plate. Most paints must be mixed with paint thinner in the ratios recommended on the paint cans before spraying.