Well that depends on the type of paint you are going to use.
Why is that? (Tutor style)
Well because automotive paint come in opaque and transparents for example.
So? Whats the difference?
Well some of those colors behave differently under same cercumstances.
A tranparent yellow can get invisible on black and bright on white, and another yellow can do the oposite for example.
In the tube they look the same, on your artwork they dont.
In the picture two different yellows, left bottom and right top look the same, but are on a different color underground.

You can see the top yellow just dissapearings on a black underground. So two bottles needed here
Your brand should have this online