The Dongfeng diesel multiple unit, also known as the Dongfeng motor coach,[Note 1] and NM1, was a DMU of Ministry of Railways, and was also the first diesel-hydraulic power car and double deck passenger car of China, built by Qingdao Sifang in 1958.

The train consisted two motors and four double deck trailers, and was designed for short, commuter services.

As the set had numerous flaws, it never entered mass production, but the valuable experience gained in the design and manufacturing process was later applied to the DFH1 and Red Star-class locomotive, while the passenger cars designs were later further developed for double deck trains such as the NZJ.

In June 1958, Sifang along with Dalian Locomotive Research Institute, Jiao Tong University and Jining railway sector proceeded to develop the Dongfeng double deck,[4] hydraulic transmission motor coach.

In 22 September, with a build time of just two months, Sifang rolled out the first set of the Dongfeng motor coach.

It was designed for short distance passenger transport, with the motors on either end of the set and having a structural maximum speed of 120 km/h (75 mph).

[6][7] By the end of September 1958, the Dongfeng was delivered to Beijing, for the ninth national railroad worker's exhibition.

In operation, various faults occurred, such as high oil temperatures, out of synchronisation valves, twisted universal joints and so on.

As the first generation of double deck passenger carriages in China, the design of the set lacked prior experience, and so the operation of these sets revealed multiple problems, such as poor ventilation leading to high temperatures in summer, water leaks reducing the resistance of electrical components, and the corrosion of the structural frame.

Motor car NM1-001 also had a 10 kW auxiliary petrol engine acting as a generator, providing power to the entire train.

Cooling fans are driven directly by the motor, after it passes through a gearbox, friction clutch and a universal joint.

The four trailers of the Dongfeng DMU were all double deck passenger cars, with the design name of 双2, numbered SK 0001–0004.

However, this design reduced space in the carriage, and made it difficult for passengers with luggage to move around easily.