At
night, police cars will sometimes be parked in 'hidden areas', such as behind a billboard or in a parking lot, and will be facing traffic looking for speeders or DWI cases. They may also be parked alongside the road or in the breakdown lane on the highway.
Ghost cars will
always have their head lights off, but sometimes the
day-running lights will remain on, giving the headlights a
light 'ghostly' appearance. It is also sometimes used to refer to any ordinary car driving at night with no headlights or just their dayrunners on, but usually the title is reserved for police vehicles.
I passed under the bridge when I noticed
two ghost cars
hiding next to it, on the median, each
facing a different direction.