Concerning the Mini, BMW bought Rover in 1994, so any Mini that was build after 1994 can basically be considered a German car.
I work in the automobile industry (in France) and well remember when BMW took over Rover... I know because Honda was very close to doing it before them but backed off, and our company received a joint Rover-Honda visit with an idea of our making certain parts for... the new mini, which was already on the boards but which Rover knew they would never survive long enough to produce.
That said, the old and new minis have always been contstructed exclusively in blighty.
Whilst this is true, The same could have been said for Volvo in GT4 as at that point they were owned by Ford, thus American.
it's a bit more complicated than that. There's Ford US but also Ford Europe, which is actually two separate subsidiaries one English and one German.
But I think that Volvo AB was directly attached to FMC (US).
But far more Volvos are built in Belgium than in Sweden.
By the same token, the biggest Ford plant in the world is in Spain.
To make things even stranger, we (a Renault subsidiary) have made parts for ALL these companies (and more).
Today's automobile world has become so interrelated that it's not too much of an exagerration to say the badge on the front of a car only means that particular company has designed its look and general performance level*, and worked out image and market strategy. then they "make-or-buy" everything across the whole industry. Everyone makes everything.
*or not even! there are many cases of the same car coming off the same production line wearing 2 or 3 different badges.