The prime mover provides a power output of 2,650 kilowatts (3,550 hp), a starting traction effort of 400 kilonewtons (90,000 lbf) and a maximum speed of 160 kilometres per hour (99 mph).

[4] Originally there were plans to order additional Di 4 units, but this was discarded and instead a new class was pursued,[5] as NSB wanted similar, but slightly more modern, locomotives.

[7] On 17 December 1997, NSB's board decided to purchase eleven of the locomotives, excluding number 664.

This was based on an agreement whereby NSB would receive compensation for the incurred losses owing to late delivery and under-performance.

One contributing factor was a 25 percent extra wage for engineers for having above-regulation noise levels in the Di 3 cabs.

[10] On 28 April 1998, NSB officially announced to Siemens that they might terminate the purchase contract, describing the locomotives as having "fundamental construction faults"[11] By July 1998, nine of the eleven units were out of service and one was returned to Germany for repairs after a fire.

When the only operational unit broke down, NSB's board sent a bill for the purchase price plus interest to Siemens, stating that if it was not paid within a week, the issue would be brought to court.

[13] By February 1999, Siemens had given up trying to fix the locomotives, although they had established that the main fault lay in the generators.

On 5 May 1999, the companies announcement that they had reached an agreement for the trains to be returned to Siemens, and NOK 485 million be compensated to NSB.

In addition to the purchase price, the compensation included interest and coverage for NSB's extra expenses.

[14] A major contributor to the faults lay in Siemen's 1992 take-over of MaK, in which a large number of veteran employees, who had the necessary competence to build diesel-locomotives, were retired.

They were made narrower by removing outside stairs and railings, and moving lights to meet International Union of Railways standards.

[14] Later lessees of one or more units included Cargolink, Chemins de Fer Luxembourgeois (CFL), CTL Logistics, Hoyer Railserv, HSL-Logistik, KEP Logistik, NetLog Netzwerklogistik, Neuss-Düsseldorfer Häfen, Norddeutsche Eisenbahngesellschaft, Osthavelländische Eisenbahn, the Port of Kiel, RSE Cargo, Regental Bahnbetriebs, Schneider & Schneider and Verkehrsbetriebe Peine-Salzgitter.

Because of a three-year waiting time for new locomotives, CFL leased the Di 6 units for freight trains between Esch-sur-Alzette, Bettembourg and Mertert.

[2][17] Since 2006, the main leaser is the Veolia Verkehr-owned Nord-Ostsee-Bahn, which operates passenger trains in Schleswig-Holstein, Germany.

[17] The diesel-electric locomotive has a MaK 12-cylinder 12M282 diesel prime mover which provides a power output of 2,650 kilowatts (3,550 hp) at 1000 revolutions per minute.

Transmission of power is by Siemens-built bogie-mounted three phase asynchronous induction type double pole pair traction motors which power the wheels via reduction gear and a hollow quill drive connected to the wheels at both ends via resilient links.

[1][2][16][19] The locomotives each have two bogies, each with three powered standard gauge axles, giving a Co′Co′ wheel arrangement.