Cop Cars have a sound all their own…no matter where they hail from. Here are a couple of examples…
First, The NYPD!

I hear (no pun intended) part of their repertoire includes the new “Rumbler” siren which emanates very low-frequency sounds you can feel. Perhaps our friends in New York City can corroborate this?
Next, Die Polizei in Berlin, Deutschland!

Eight others are found over at Jalopnik. Whichever siren you identify with, that’s the one heralding the Overnight Open Thread!