The most basic paint jobs could be done with an air compressor with 15 psi of air pressure and 10 horsepower that can paint roughly 20 cubic feet per minute (CFM). Stronger air compressors will be more efficient. Some colors depend on more air pressure or CFM, so check recommendations for the paint job you have in mind for more detail. As for tank size, you can paint with smaller tanks, but a 60-gallon tank will help ensure that you can paint the whole car without having to refill the tank.