You don't even need to have a cop in the unmarked car. You can have a remotely viewable camera that the desk-duty cop watches from the precinct headquarters.
EDIT to address the troll: you can run these off of a car battery and stream it over the cellphone network. Quality will be rather good even then. If you can park a car, you can set up the camera. PTZ, too.
"don't mind me poor 100% black community im just here from ADT to install this randomly hallarious HD camera and wireless antenna facing this decrepit house"
Having built them for the ATF, there are concealable cameras that mount to light poles and run off grid power. There are also concealable cameras that look like fire hydrants, high voltage signs, rocks, and cars that are designed to feed the video back wirelessly and be rapidly deployable.
The typical utility company truck (gas, electricity, water) can be parked outside and someone could install any number of objects that contain cameras/microphones, but don't look like one. Resorting to an obvious strawman does nothing.
That would be dangerous for the utility company employees, because this tactic would quickly become known, and all utility vehicles and employees would then be viewed with hostility and suspicion by criminals and other residents.
Similar to the vaccination blowback after the Bin Laden raid.
EDIT to address the troll: you can run these off of a car battery and stream it over the cellphone network. Quality will be rather good even then. If you can park a car, you can set up the camera. PTZ, too.