Silverliner is the name given to a series of electric multiple unit (EMU) railcars in commuter rail service in the Philadelphia area since 1958.

While 100 of the MP54s had been rebuilt in 1950 with increased power and air conditioning, the old cars still suffered from a small passenger capacity, high weight and poor acceleration among other things.

As other railroads adopted new technology MUs like the New York Central ACMU and New Haven 4400 series "Washboards" the PRR felt increasing pressure to update its fleet.

In 1958 the PRR placed an order with the Philadelphia-based Budd Company for 6 Pioneer III MU cars in two subclasses to test out various options.

However, as testing went on they were soon limited to suburban service in the Philadelphia area when a full-scale production order of 38 PRR "Silverliner" cars were delivered in 1963.

[2] The Pioneer III cars suffered from a low capacity main transformer as well as gearbox issues and a complex propulsion system that coupled highly sensitive mercury arc ignitron rectifier tubes with an inefficient DC resistance motor controller.

In the late 1980s SEPTA purchased a number of push-pull trainsets to provide enough peak period capacity to retire its remaining Reading Blueliners and the Silverliner Is by the timetable that took effect April 1, 1990.

Although there were plans to convert the cars into locomotive-hauled coaches, SEPTA finally decided to dispose of the fleet due to the expense it would have taken to deal with PCBs in the transformers and the lack of ADA compliance.

As a result, state and local government stepped in to purchase new cars that would be in turn used by the private railroads to run the required commuter operations through an entity known as the Passenger Service Improvement Corporation.

While some referred to the new vehicles as "PSIC Cars", the modern stainless steel body shells quickly defined the fleet and the name "Silverliner" was soon adopted.

[3] Although funding for the service was being provided by the newly formed SEPTA, from 1963 until the formation of Conrail in 1976, the Silverliners were operated by and wore the livery of their respective railroads, the PRR Keystone being replaced by the Penn Central "Worms" in 1968.

[5][failed verification] At some point the old mercury arc rectifiers were replaced by the more reliable silicon controlled variety, the HVAC was updated with ozone safe refrigerant, the PCBs were removed in the transformer coolant and the bathrooms were closed in those cars that had them.

By the year 2000 SEPTA began to plan for the retirement of the Budd Silverliners, which had not only reached the end of their design life, but their lack of dynamic brakes and manually worked doors were presenting growing operational headaches.

However a prolonged procurement process as well as delays in delivering the replacement Silverliner V cars resulted in the Budds lasting in service well into 2012, a run of nearly 50 years.

Other differences included carbody sides without traditional railroad letterboards, wider stainless steel fluting, fiberglass cladding on portions of the car ends, full-length overhead luggage racks on both sides of the cars, and rectangular interior door windows in place of round portal windows seen on the Budds.

[5][failed verification] In addition to suburban duties the Silverliner IIIs were used on longer distance runs to Harrisburg, Pennsylvania, replacing PRR MP54E5 and E6 cars.

Starting in 2011 with the first deliveries of the new Silverliner Vs, those IIIs not already sidelined by mechanical issues began to be retired, a process completed by June 2012.

[6] Aside from the boxier look and smaller side windows, the main changes between the new IVs and earlier Silverliners included a dynamic brake system, for which the resistance grids were fitted in the car's signature roof hump, and, for the Penn Central cars, a trainline automatic door system which removed the need for train crew to manually open doors at high level platforms.

A readily apparent external feature of the Silverliner IV is a windowed body panel plug in the middle of the cars on each side, a provision for high-platform-only center doors which have never been installed, in contrast with New Jersey Transit's similar, contemporary Arrow II and III cars which were built with such operating center doors.

Delivery of the Silverliner IVs was briefly interrupted by the production of 70 Arrow II cars for the New Jersey Department of Transportation before the Penn Central received 96 pairs numbered 304 through 399.

[9] On February 7th, 2025, A SEPTA commuter train made up of Silverliner IVs, carrying 350 people onboard caught fire in Ridley Park, Delaware County, Pennsylvania.

[11][12] The last of these cars was received by SEPTA in March 2013, three years behind schedule due to a variety of production problems, resulting in contractually specified delay penalties against the manufacturer totaling over $20 million.

The new trains feature enhanced security, with CCTV cameras that are able to broadcast over a proprietary wireless network to the Command Center at SEPTA's headquarters.