[8] A fourth order for an additional 15 was placed by KiwiRail in 2016, to replace the EF class electric locomotives on the North Island Main Trunk, but the decision to scrap the electrification was later reversed.

[9] The DLs were the first newly built diesel-electric mainline locomotives on New Zealand's rail network since the DF class was introduced in 1979.

Soon after the new company was officially launched, the State-Owned Enterprises Minister Trevor Mallard announced that the government was investigating the possibility of assembling new locomotives at Hutt Workshops, then operated by United Group Rail, from imported parts and based on the Arakaha concept.

In March 2009, the government announced that it had authorised KiwiRail to invest $115m in new rolling stock: $75m for 20 locomotives, and $40m for new carriages for Tranz Scenic.

[17] The idea of building the locomotives in New Zealand as advocated by the Labour government was promoted as a way of creating jobs at a time when the economy was entering a recession and unemployment was rising.

Critics of the idea pointed out that New Zealand did not possess the necessary skilled labour in sufficient quantity for such a construction program to proceed in a timely manner, and had not done so for several decades since New Zealand Government Railways ceased building its own locomotives - all mainline locomotives since the introduction of diesel traction in the 1950s have been imported.

The cab layout incorporates design elements from British Rail Class 60 with a near-central pedestal controller.

The first six arrived at Mount Maunganui on 20 November 2010,[1] and were moved to Te Rapa, Hamilton three days later for commissioning and driver training.

[25] A ceremony to mark commissioning was held at Te Rapa on 10 December, attended by many KiwiRail staff, including CEO Jim Quinn.

[26] The first six were used for driver training and rail system compliance testing,[4] and the NZ Transport Agency gave the locomotives certification for New Zealand in May 2011.

[32] In 2012 KiwiRail undertook testing of a DL locomotive along the lower North Island main and branch lines.

As a result, KiwiRail employees were told not to enter the alternator compartment and to keep doors to the area closed when the engine is running.

[7] As a consequence of the problems experienced, production of the second batch of units was put on hold in mid-2012 pending resolution of the design issues.

[7] On 31 July 2012 KiwiRail announced that the fleet achieved its highest mean distance between failures (MDBF) rating, outperforming the DX class locomotives by 3000 km.

In October 2022 two DL class locomotives traveled from Westfield in Auckland to the Makarau Tunnel for clearance testing.

The Linesider magazine stated in its December 2022 edition that DL operation on the North Auckland Line is "likely to begin later this year.