The AJD is a family of V6 and V8 turbodiesel engines with a clean-sheet architecture and variable valve timing developed by Ford of Europe for its then-subsidiaries Jaguar and Land Rover, as well as for its partner PSA Group working under the Gemini joint development and production agreement. It is called the AJD-V6 in the Jaguar and Land Rover vehicles and the DT17/DT20 by Citroën and Peugeot. The engines share the same bore/stroke ratio, with the V6 version displacing 2.7 L (2,720 cc) and the V8 version displacing 3.6 L (3,630 cc). The V6 and the V8 were launched in 2004 and 2006 respectively. The V6 engine meets the Euro IV emissions standards. A DT20 3.0 L (2,993 cc) was added in 2009 and is based on the DT17 2.7 L (2,720 cc). The V6 is used across many vehicles, from the Citroën C5 and C6, to the Land Rover Discovery, Range Rover, multiple cars in the Jaguar range, and also the Ford Territory and next gen Ford Ranger.

A V8 engine is an eight-cylinder piston engine in which two banks of four cylinders share a common crankshaft and are arranged in a V configuration.