The police often use unmarked police cars to carry out both speed enforcement and road patrols. I understand that their use is increasing as they are less noticed by the wider community and therefore less likely to be brought to the attention of other drivers (e.g. flashing lights or CB announcements).
We saw several in use and only new they were unmarked police cars when they were pulling over vehicles as they had flashing blues in the rear and front windows. If these were not going, they would have been very hard to identify as police vehicles.
In relation to signage for speed camera vans, there is no legislative requirement to display such signs. This link indicates why the signs may be used, but maybe these signs are also displayed to reduce the number of complaints to police/local authority for inappropriately parked vehicles.
I wouldn’t call them revenue raising as in a perfect world they wouldn’t raise anything. If you don’t speed, then they shouldn’t be an issue and one won’t be supplementing the States coffers.
