turret light
n.— «None of the unmarked police cars on the street displayed “turret lights.”» —“Three Men Who Had No Reason to Run” by Jim Dwyer New York Times Apr. 5, 2008. (source: Double-Tongued Dictionary)
squadrol n. a police vehicle that serves the purposes of both a patrol wagon and squad car. Etymological Note: squad + patrol (source: Double-Tongued Dictionary)