How many cubic feet of air to paint a car?

I used a 5 hp, 230 volt, 2 stage, 80 gallon tank that ran up to 150psi. It had a switch on it so that it would not shut down after it was up to pressure, it ran constantly, and only loaded and unloaded when needed. Spray gun only required 20psi. I put down 2 coats of primer, 3 coats of base and 5 coats of clear.

No problems with lack of air with that sucker.