Nice: We had those Kadetts and Mantas and like 1000 of them in my hometown when I was a kid('70s)
Also the GT was not uncommon.
It was always a thing between Volkswagen(Beetle/Golf/Scirocco) and Opel where I'm from.
My fav Opel of all time, Manta 400. And one of my fav rallydrivers ever.
@2:13.....Legendary....
Cheers
Robin