The new Mini diesels use a BMW engine rather than the PSA engine. The engine which is used is the BMW N47 common rail diesel unit which first came out in the 5 series BMW, it then ended up in the 3 series, 1 series and now the Mini's. The main difference between say the 318d and 320d is the way its tuned, its the same engine! I'm not 100% how they change capacity on the unit for use as a 1.6 litre unit, maybe change the stroke or something but essentially the unit in my One D Clubman is the same engine which powers my Dads 2008 520D. Witihn the limitations of the capacity, the only difference is the way its tuned. So as with the 318D and 320D, the One D and Cooper D use exactly the same engine and therefore in theory it would not take much modification to make a One D a Cooper D. I think the N47 1.6 litre is also in the 1 series BMW as the 116D and is in the Countryman as the One D and Cooper D and I think the Cooper SD as the 2 litre unit. Basically the N47 is in everything BMW Diesel related, until you get to the 6 cylinder engines. I'm not sure if there are any small hardware modifications between the One D and Cooper D as part of the tuning but the main unit is defo the same.
Mini One D Clubman R55 2012 (61) AKA Lewis | Velvet Silver | Pepper Pack | Roof Rails | Black C Pillars | 16" 6 Star Twin Spokes |