I brought this up to Crap-Head early in the alpha testing but he just set it aside for another day. Well it is another day so I shal remind you guys of it.
In all emergency vehicles, the lights and sounds only render/play on your client if the vehicles origin is in your FOV. That means if you are in an ambulance driving in first person, you cant hear the siren nor see the lights, even if they're playing. This also means if there are emergency vehicles behind you or the cops are trying to pull you over, you will not hear it.
It would be nice for people to actually pull over instead of driving along because they cant hear the siren.