Question on paint coverage and volume

[Blue70]

Ok, this might sound dumb, but I am thinking of repainting my Road Runner
and am trying to price it all out, but I am unsure about the coverage as
I have never done a whole car before, only hoods.

So I guess for you painters the question is
How much paint do you think it would take to cover a 74 Road Runner?
its a BIG car, you dont realize it till you see it next to a friends 68 Charger
and it makes IT look small, and its as long as my new quad cab HEMI ram..
I want to be sure that I order a safe amount so that I dont run out mid paint!