Someone please correct me if I'm wrong, but based on dialog I have had with legal types it is my understanding in Oregon (not WA) your car is not considered private property in the terms of a dwelling or actual land. Thus, if you have a firearm in your car and you drive onto work's owned parking lot your rights are superseded by the property owner of the land you drove upon. It appears that maybe in WA this isn't the same way based on the rulings.
This varies widely state to state.
You must be referring to the appeals court ruling on Bryan Ward vs State of Oregon. It basicaly says your car is a public place while operated on public roads. It says nothing about ownership while on private property.
Oregon Firearms Federation