Diamond DA40 NG (diesel)

Diamond Aircraft introduced the DA40 NG in 2010 as the diesel-engine variant of the DA40 family that had been in production since 2002. The NG (Next Generation) designation reflected the airplane's modern avionics (Garmin G1000) and the Austro Engine AE300 turbo-diesel powerplant. The AE300 is a Mercedes-Benz OM640-derived 4-cylinder turbocharged common-rail diesel engine designed specifically for aviation use. The engine runs on Jet A, Jet A-1, or diesel fuel.

Production has continued through generation refinements. The DA40 NG fleet has grown substantially as European and international flight schools have adopted the airplane for primary training in markets where Jet A is meaningfully cheaper or more available than 100LL. The DA40 NG has also been adopted by US flight schools and personal owners seeking the diesel's economic and operational advantages.

Diamond also produces the Lycoming-powered DA40 (standard piston model with IO-360-M1A engine, which we cover separately in the standard DA40 page). The two variants share airframes and most systems. The NG specifically refers to the diesel-engine variant. Austro Engine has refined the AE300 over the production run, with the current variant offering improved fuel efficiency and longer TBR intervals than the original.

The DA40 NG cruises at about 154 KTAS at high cruise power, burning 8.5 gph of Jet A. At long-range cruise, the airplane drops to about 130 KTAS on 5.5 gph. The diesel engine's torque characteristics give the DA40 NG strong climb performance, especially at altitude. Service ceiling is FL160 (operational) with the Austro engine maintaining strong power output at altitude due to the turbocharger.

Useful load on a DA40 NG is about 825 to 900 pounds. Full fuel (39 gallons usable plus optional auxiliary tanks) leaves about 450 to 525 pounds for people and bags. Four adults of typical weight plus light luggage fit within gross with careful loading. Range with reserves is about 940 nm at long-range cruise on standard fuel. The fuel-efficient operation makes the DA40 NG one of the longest-range four-seat singles in its acquisition class.

The Austro AE300 is the engine on every DA40 NG. Four-cylinder, in-line, turbocharged, intercooled, common-rail diesel rated at 168 hp at 2,300 RPM. Austro Engine's published TBR (Time Between Replacement) is 1,800 hours or 12 calendar years. Unlike piston aviation engines, the AE300 is designed to be replaced rather than overhauled at TBR. The engine is sealed at the factory and not field-rebuildable.

Engine replacement at TBR runs $90,000 to $120,000 installed in 2026 prices. This is a major ownership cost item that distinguishes the DA40 NG from Lycoming or Continental-powered alternatives. The replacement engine comes from Austro factory exchange with a fresh TBR cycle. Pre-buy must verify current engine time and remaining TBR cycle as a major pricing variable.

Oil consumption on the AE300 is essentially zero between scheduled oil changes (every 100 hours). The engine has substantially different operating characteristics from gasoline aviation engines. The FADEC (Full Authority Digital Engine Control) system simplifies pilot management and provides automatic mixture and timing control. The Hartzell or MT-Propeller constant-speed propeller standard on the DA40 NG requires periodic overhaul at $3,000 to $5,000.

Plan on $200 to $280 per flight hour at 100 hours a year of utilization, all-in. The DA40 NG's operating economics are distinctive due to the diesel fuel and engine-replacement model. Fuel costs run about $42 to $60 per hour at 8.5 gph and $5 to $7 for Jet A (variable by region). Engine replacement reserve is $50 to $67 per hour based on $90,000 to $120,000 replacement amortized across 1,800-hour TBR. Airframe maintenance reserve is $25 to $40 per hour due to composite construction and Austro-specific items.

Annual fixed costs (hangar, insurance, annual inspection) add another $65 to $115 per hour at 100 hours a year of utilization. Insurance on the DA40 NG is moderate. First-time owners pay $2,500 to $4,800 a year typically.

Acquisition cost in mid-2026: A DA40 NG with mid-time engine and standard G1000 panel runs $375,000 to $475,000. A DA40 NG with fresh engine and modern G1000 NXi runs $475,000 to $675,000. Engine time remaining before required replacement is the dominant pricing variable.

Diamond Aircraft and Diamond Aviators online community provide type-specific support. Austro Engine service through Diamond authorized service centers.