Ambulances serving Epping Forest district are to be replaced by a modern fleet.
The East of England Ambulance Service Trust vowed to improve response times following criticism from the Care Quality Commission.
Chief executive Dr Anthony Marsh made it one of his priorities to improve the fleet when he took the position at the beginning of the year.
He said: “We need to get more ambulances on the road treating patients and we also need to ensure that those ambulances meet the needs of both the crews and the people they care for.
"It is my ambition for us to have no ambulance or response car that is more than five years old.”
A total of 120 ambulances will be replaced by the end of April, while 68 new rapid response cars will be in use by June.