Catherine,
#11 is definitely moving in the right direction.
But, the name of our organization is too small and too hard to read in the swoosh.
Also, the ambulance looks more like a truck than an ambulance. So, I think you can do one of two things... you can either try to incorporate the idea of flashing red lights like #5 or you can move toward a little more stylized treatment of the ambulance like #16.
Brett