From the Did You Know Under the Hood Dep’t:

This EP6DT is a 1.6 Turbo charged, 4 cylinder inline engine, which forms part of the Prince family of engines, (not to be confused with the Prince Motor Company) is used extensively, in various outputs, across the Citroën/Peugeot range of vehicles.  It is also used in some BMW 1 series and Mini models.  The EP6DT is gasoline direct injection with 150 PS and special low pressure die cast cylinder head and replaced the TU line of PSA engines

    EP6DT Prince engine

Many Citroën/Peugeot power plants have been shared with other manufacturers: 

The Douvrin family (found in the CX) , formally called ZDJ/ZEJ, was an all-aluminum inline-four engine made in a joint-venture between Peugeot and Renault in the 1970s.  (More info at: https://wikivisually.com/wiki/Douvrin_engine)

The PRV was shared between Peugeot, Renault, and Volvo, thus the “PRV” name. It was produced from 1974 until it was phased out in favor of the PSA ES engine in 1998.  (More info at: https://ranwhenparked.net/2010/09/14/what-lies-beneath-the-controversial-prv-engine-part-3/).

Citroën’s HDi engines were built as part of a PSA joint-venture with Ford Motor Company..  In 1998, PSA entered into a joint venture with the Ford Motor Company to produce a range of new diesel engines. The joint venture made identical engines which were fitted to a variety of vehicles from a range of car manufacturers. The engines were assembled in production plants in the cities of Trémery and Douvrin for PSA in France, at the Ford Dagenham plant in the UK, and Volvo Engine Plant in Skövde Sweden when Volvo was still under Ford ownership.  The Ford partnership ended in 2014.   (More info at: https://en.wikipedia.org/wiki/PSA_HDi_engine).