[ZLP955]

Vauxhall Motors had it's origin in 1857 and was the wholly-owned UK subsidiary of General Motors from 1925; Opel Automobile was the Continental equivalent from 1929 after GM bought an 80% share, so interestingly Vauxhall pre-dated Opel in that regard - although it then came under Opel as the parent company.
There was a great deal of commonality, often just a badge change, but the Firenza was a Vauxhall design and assembled only in the UK and SA.
Growing up in the UK, I remember looking out for the subtle differences between the Vauxhall and Opel models, as there were often imported versions sold in parallel. The town I grew up in had a large Army base, and enlisted troops rotating in from bases in Germany often took advantage of their entitlement to import personally-owned vehicles that they had bought while stationed overseas, without import taxes. The local used car market was very busy, with sometimes exotic cars being sold (for a nice profit) by returning servicemen. Quite a lot of American cars turned up locally too, as the British soldiers frequently traded cars with the US servicemen based over there.