Nissan vans are rebadged Renaults,and Nissan use DCi engines in many of their cars,including the new Micra.
The Peugeot 806,Citroen Synergie and Fiat Ulysses were all the same,as are the Commercial derivatives(Expert,Scudo etc).
The Citreon zx and Peugeot 306 are identical mechanically,as are the 106 and Saxo.
Many GM(Vauxhall/Opel) parts are used on Saabs.
The Peugeot 1.9 diesel and
diesel engines have been used in Rovers,Ladas,Citroens,Fiats and many others...(In fact the Rovers used a Peugeot engine and a Volkswagen gearbox,the only part made by Rover was the plate to mate the two together!) and the newer Peugeot HDi units are used by many,including Jaguar(V6 HDi diesel in the X-type and Peugeot 407 etc..)
Many Audi,Volkswagen,Seat and Skoda parts are the same.
Volvo and Renault have shared engines between themselves for years.
The Nissan Terrano and Ford Maverick are the same.
The Mazda MX6 and Ford Probe were the same mechanically,and Suzuki used Mazda Diesel engines in the Vitara.
There are many other examples.......