It very well could be an inspection vehicle. Sometimes governments use vans because the inspection team consists of many poeple and/or it has space for any additional inspection equipment. The light on top of the vehicle is typical for government because sometimes the vehicles may enter certain areas where it is required to have a flahing light on top of the vehicle for safety reasons.

That being said since we do not have a confirmation on the license plate this is all speculation, but good speculation nonetheless.

Here is an inspection vehicle for NASA for example provided in the link below.

http://www.nasa.gov/mission_pages/shuttle/beh..._team.html

The main point here is yes, governments have and own many vehicles to perform various tasks.