By 2012, the DA42 had become a key revenue generator for the company, having gained popularity with government and military operators in addition to the civil market that had suffered as a result of the Great Recession.

Since its founding in the 1980s, Austrian manufacturer Diamond Aircraft Industries had concentrated on building an extensive product line.

[5] This concept emphasised several key qualities, including the need for the aircraft to be simple to operate and fuel-efficient, while providing a luxurious four-seat passenger compartment akin to modern automobiles.

The concept was not popular at the time; Aerospace publication Flying Magazine referred to Diamond's choice to develop a twin-engined aircraft for general aviation use as "the emergence of an all-new light-piston twin in this class something of a surprise.

"[5] During April 2004, the DA42 Twin Star received certification from the European Aviation Safety Agency (EASA) under the latter's newly-introduced Part procedures.

At the time of its introduction to service, aerospace publication Flight International observed that "The DA42 has no natural competitors in its class and sets a benchmark for European general aviation".

[1][10][11] In March 2009, Diamond achieved EASA certification for the Austro Engine AE 300, which enabled the DA42 to resume production.

[17] The Diamond DA42 Twin Star is a twin-engined low-wing cantilever monoplane, commonly used as a general aviation aircraft for touring and training purposes.

[4] The airframe is composed of composite materials, making extensive use of carbon fiber reinforced polymers throughout its structure; this construction provides the aircraft with a suitable passive safety level to conform with the established European Aviation Safety Agency (EASA) Part 21 rules, as well as relatively efficient aerodynamics and essentially unlimited airframe life.

[4] The pilots are housed under a sizable canopy which provides generous external visibility, save for the use of a large fixed sunscreen.

Additionally, separate baggage compartments, which are accessible via external hatches, are contained within internal space in the aircraft's nose.

[4] Both longitudinal and lateral stability can be maintained with a relatively low level of effort, not necessitating continuous trimming while the aircraft is accelerating.

DA42 NG climbs at up to 270 ft/min at sea level in standard conditions on a single engine, with performance degrading with higher altitudes and temperatures.

Although engine displacement had increased, it was deliberately de-rated in order to produce the same power 101 kW (135 hp) and torque 409 N⋅m (302 lbf⋅ft) as the earlier 1.7 L.

[21] In late 2007, Diamond announced it would begin building and installing its own aerodiesels, through a subsidiary, Austro Engine GmbH, in collaboration with other partners that included Mercedes-Benz.

[32] During the latter part of 2008 and early 2009, a pair of Royal Air Force DA42 MPPs were deployed for eight months to provide combat support to coalition forces operating in Iraq; during the deployment, these aircraft flew a combined 2,000h in the surveillance role, for which it had been outfitted with Cineflex high-definition cameras, Riegl laser scanners and Scotty satellite communications kit.