Diesel locomotive set, and went into series production with other streamlined car sets in Germany starting in 1935. In the USA, diesel-electric propulsion was brought to high speed mainline passenger service in late 1934, largely through the research and development efforts of General Motors from 1930–34 and advances in lightweight carbody design by the Budd Company. The economic recovery from the Second World War saw the widespread adoption of diesel locomotives in many countries. They offered greater flexibility and performance than steam locomotives, as well as substantially lower operating and maintenance costs. Diesel–hydraulic transmissions were intrdouced in the 1950s, but from the
New Zealand DL class locomotive eight would be ordered to replace the EF class electric locomotives on the NIMT. This will result in an intended class total of 71 DL units. The DLs were the first new-build diesel-electric mainline locomotives on New Zealand's rail network since the DF class was introduced in 1979. The order marked one of the first steps of considerable investment in KiwiRail, and the first order for a Chinese-built locomotive from a western country. The acquisition of new locomotives was first proposed by Toll NZ after they purchased Tranz Rail in 2003. When Toll assumed responsibility for the rail operation, the