Special Constable Jacob Milanov also altered his uniform to remove the letters SC.
Following a Met Police misconduct hearing on December 17, SC Milanov was dismissed without notice.
Officers on duty on July 12 were alerted to a fake emergency response car driving in west London.
The vehicle was fitted with emergency warning equipment including blue lights and sirens.
Inside the car, officers found hand-held radios, a police memo pad, evidence bags, gaffer tape and the altered police uniform.
SC Milanov admitted that he had arranged for the vehicle to be fitted with lights so as to resemble an emergency vehicle.
He admitted when asked that he occasionally used the blue roads on “side roads”.
Officers established that SC Milanov drove his car with blue lights and a siren on at least eight occasions between June 14 and July 6.
These included in Parliament Square, Westminster Bridge and Chelsea Bridge.
Commander Andy Britain said SC Milanov put the safety of others at risk as other drivers might have taken evasive action in response to the blue lights.
Commander Britain concluded SC Milanov should be dismissed without notice and be placed on the College of Policing’s barred list.
