Wikipedia says simply visible in vehicle, needn't be locked container.
Open carry is generally allowed without a permit for people 18 years of age and older. The following cities and counties have exceptions that disallow the open carry of "assault weapons" (any firearm that is equipped with a magazine that will hold more than 20 rounds of ammunition or is designed by the manufacturer to accommodate a silencer or equipped with a folding stock) or shotguns equipped with a magazine that holds more than 7 rounds: the Cities of Alexandria, Chesapeake, Fairfax, Falls Church, Newport News, Norfolk, Richmond, and Virginia Beach and in the Counties of Arlington, Fairfax, Henrico, Loudoun, and Prince William. These restrictions do not apply to valid concealed carry permit holders. Stated differently, you may open carry an assault weapon/shotgun with more than 7 rounds with a permit in the aforementioned locations, but do not need a permit to do so in any other locality in Virginia.
For open carry in a vehicle, the firearm must be "properly secured in a container or compartment within the vehicle" (ie glove box, center console, trunk, etc). The container/compartment does not have to be locked, the firearm may be within the reach of the driver or a passenger, and the firearm may be loaded. This does not preempt an employer from prohibiting firearms "at a place of employment if there is a company policy or signage prohibiting firearms on the premises." Furthermore, a "county or city may by ordinance make it unlawful for any person to transport, possess or carry a loaded shotgun or loaded rifle in any vehicle on any public street, road, or highway within such locality." However, this does not "apply to duly authorized law-enforcement officers or military personnel in the performance of their lawful duties, nor to any person who reasonably believes that a loaded rifle or shotgun is necessary for his personal safety in the course of his employment or business."
In addition, a firearm may be considered "open carry" in a vehicle if the firearm is openly visible, though this is not as well established as the "secured in a container/compartment" rule.