(a) The regulation of the speed of a vehicle under this subchapter does not apply to:
(1) an authorized emergency vehicle responding to a call;
(2) a police patrol; or
(3) a physician or ambulance responding to an emergency call.
(b) A municipality by ordinance may regulate the speed of:
(1) an ambulance;
(2) an emergency medical services vehicle; or
(3) an authorized vehicle operated by a blood or tissue bank.