I pulled my fenders, doors, and hood off... left the bed on though. I sprayed 3 coats on the entire truck, jambs, inside of fenders, and underside of hood with 1 gallon and had a little left over. I did not paint the inside of the bed since I have a liner. I think I had plenty left to do it though if I had wanted.
I'm not a painter though, and that's a single stage paint, not BC/CC, so take that with a grain of salt.