The occupying powers left the Polish State Railways with a limited number of rail cars of different types. The most numerous group was 20 Wittfeld's two-car accumulator sets (built from 1907 to 1914), with a range of up to 81 miles (130 kilometres) and a capacity of 150 passengers. They were in operation in the area of the Poznań and Toruń directorates. In the territory of the Kraków directorate five Komarek two-axle third class steam cars with 32 seats were in service. They carried passengers on the route from Skarżysko to Ostrowiec Świętokrzyski, Radom and Końskie.
In 1928 a Clayton steam wagon was bought for the Tarnów – Szczucin line. At the same time, the Lilpop, Rau and Loewenstein Factory assembled a self-propelled wagon for the Puck – Hel line using Sentinel-Camel's subassemblies, and the “Cegielski” Factory in 1931 supplied 9 steam-powered wagons according to modified documentation. Thus, various attempts were made at giving up steam locomotives, but still steam was used to power the vehicles.
The first diesel rail cars were put into service by narrow-gauge railways: in Wilanów and Gniezno. In 1926, the railway in Wilanów bought such wagons in Germany. The four-axle self-propelled wagons were produced by the Lilpop Factory. Also, the Warsaw Commuter Railway Workshops built a number of wagons and small diesel locomotives of various design.
On the other hand, the first normal-gauge diesel wagon (Ganz) with a trailer car was put into service in 1928 on the line between Kraków and Kocmyrzów. Simultaneously, experiments were carried out involving an extremely fallible diesel wagon produced in 1910 by Düsseldorfer Eisenbahnbedarf. Despite it being completely refurbished in 1931, its performance was still unsatisfactory and it was phased out.
The period 1931 – 1932 was a time when different models hired from the manufacturers were tested but they failed to meet expectations. In 1933 an Austrian manufacturer, Austro-Daimler-Puch, offered a T2x640 H4 rail car with two petrol engines and wheels with pneumatic tyres which absorbed shock during the ride. The wagon passed the test and was purchased for the rail car depot in Kraków. Due to its elongated shape it was referred to as “Luxtorpeda”.
Good performance of this machine encouraged domestic manufacturers to take an interest in the production of diesel wagons. Having introduced improvements and changes according the modernised Austrian documentation, the factory in Chrzanów produced 5 Luxtorpedas in 1936. The machines supplemented the rolling stock of the Polish State Railways after test rides from Kraków to Zakopane, Krynica, and to Warsaw and Lviv. The maximum travelling speed was set at 72 mph (115 km/h). A ride by a Luxtorpeda from Kraków to Zakopane considerably reduced the travelling time. Even though the train arrived in Rabka, it took 2 hours and 18 minutes to complete the whole route. A Luxtorpeda wagon had driver booths on both ends. Changing the direction of travel, which happened twice on this line, the driver had to walk from the booth on one end of the wagon to the one on the other end.
New designs were also adopted by other domestic manufacturers. In 1934 the Lilpop, Rau and Loewenstein Factory supplied 2 four-axle and 12 two-axle rail cars along with trailer cars. Up to 1939 the Cegielski Factory produced 28 four-axle rail cars with Saurer motors, and the combined Royal and Laura Steelworks built a wagon with the Diesel-Simmering motor.
Fablok in Chrzanów commenced its adventure with diesel traction from 10 covered and 10 open draisines ordered by the Polish State Railways (1930). The first diesel locomotive of domestic origin was the G1C produced in Chrzanów. It was a two-axle locomotive with a 60 HP Diesel-Warchalowski motor (1930). Regrettably, it was not effective on a mine siding due to insufficient motor power and was returned to the manufacturer. As regards the needs of private customers, according to the documentation bought from the Deutz factory, Fablok produced 12 two-axle normal-gauge locomotives of 3 types, one three-axle locomotive and one prototype.