The R44 was the first 75-foot (22.86 m) car for the New York City Subway. It was introduced for IND and BMT service because it was thought that a train of eight 75-foot (23 m) cars would be more efficient than ten 60-foot (18.29 m) cars. Even with an overall increase in length, the R44s had only eight sets of doors per car (Ten 60-foot (18 m) cars have 40 sets of doors whereas eight 75-foot (23 m) cars have only 32 sets of doors).
To be sure that the system could accommodate 75-foot (23 m) cars, two retired R1 cars (numbered 165 and 192; renumbered XC675 and XC575 respectively) were cut in half, lengthened to 75 feet (23 m) and sent to various places around the subway and the Staten Island Railway. It was determined that the BMT Eastern Division (the J/Z, L and M services) would be too difficult to convert to allow 75-foot (23 m) length cars, so this was not done.
The R44s were the last subway cars built by St. Louis Car Company, which in 1974 left the rail transit car business after the order was completed, due to various technical problems that plague these cars to this day.
The R44s came in singles which needed each other to run, much like the "Protestant Marriages" of the R26/27/28/30s. These were later married after overhaul into ABBA sets of four cars. A cars are evenly numbered cars with operator cabs. B cars have odd-numbers and no cabs.
The interior design departed drastically from previous models. The R44 had orange and yellow plastic bucket seats, a feature which many later models would later incorporate. The seats were protected from the doorways by faux wood and glass panels. The walls were tan with "wallpaper" featuring the seals of New York State and New York City.
This system continued onto the subsequent R46 cars.
The R44 was the first subway car since the BMT Green Hornet to incorporate a warning tone that sounds immediately before the doors begin to close as the train prepares to leave the station. The tone consists of two notes which are often described as "bing-bong" since they are the same as the first two notes of the Westminster Chimes. This has become the signature sound of the New York City subway and is still used with new cars.
The R44 also set the world speed record for a subway car. On January 31, 1972, a consist reached a speed of 87.75 mph(141.2 km/hr) on the Long Island Rail Road's main line between Woodside and Jamaica. With two motors per car disabled, the train still reached 77 mph. The cars were capable of even higher speeds, but the length of the test track was insufficient to allow further acceleration.
During the General Overhaul Program (GOH) from 1990–92, the R44's were rebuilt by NYCTA at 207 Street Overhaul Shop in Inwood, Manhattan; Coney Island Overhaul Shop in Brooklyn (cars 5342-5479); and Morrison-Knudsen (cars 5202-5341). The blue stripe was removed and painted gray. Since this stripe was carbon steel, it is now beginning to rust. The rollsigns on the sides of the cars were replaced with electronic LED signs which remain today, with the exception of the 64 SIR cars which had their rollsigns removed and never replaced. The cars were also given four-digit numbers. They previously had three-digit numbers.
The R44 Staten Island Railway cars are also known as R44 SI or MUE-2. The Staten Island Railway's 64 R44 type cars are modified to FRA standards for passenger equipment running on a freight road. Cars are numbered 388-466, all single units with couplers (no permanent sets), with 436-466 even numbers only. 388-399 are transfers from the subway system. Before the R44 cars are replaced, they are getting new floors, new blue bucket seats and new logos for the SIR R44 cars.
The MTA planned to replace the R44's with the R179's, but with many issues involved, they were retired by the R160s instead. The R44s on the Staten Island Railway are still in operation. They will get replaced in at least 2023, upon the arrival of the R211.