The Metropolitan cars were also the catalyst of change for their respective systems as the high-level boarding required all stations in the electrified zone to be rebuilt between 1966 and 1968, and the increased power demand forced the LIRR to update its third rail power supply from 650 V DC to 750 V DC to take advantage of the car's performance. On December 30, 1968, the M1s went into revenue service, with the first revenue train being an 8-car local from Babylon to Penn Station.
The introduction of the Metropolitan cars led to significant changes in the LIRR system.  Stations within the electrified zone were rebuilt between 1966 and 1968 due to the need for high-level boarding, and the power supply was upgraded from 650 V DC to 750 V DC to support the cars' performance. The first revenue train using the M1s ran on December 30, 1968, with an 8-car local departing Babylon for Penn Station.