[Dave72dt]

is the interior getting painted as well? How about the firewall, underside of the hood, jambs? Any parts that will be painted front and back that weren't from the factory? That all adds to the surface area and a panel has a lot more than a car. A gallon may be close on the exterior only. You'll know after the first coat goes on how much it takes per coat and you can get extra mixed at that time if needed before applying the second and third coats. Mix the extra in with what's left of the original batch, then spray the second and third coats and you won't have a shade change problem. It's always nice to have extra for touchups or repairs