Yeah, Opel and Vauxhall are the same thing really, plus Holden. All owned by General motors, and even today they all share many different cars rebadged as Vauxhall, Opel, Holden.
I have certainly seen the old 80's Commodores sharing the same body shape as a Vauxhall/Opel Carlton. Stealthy's model looks like a Vauxhall Senator though, which was a slightly bigger version of our Carlton, with the added rear quarter window.
Vauxhall Senator
Vauxhall Carlton/Lotus Carlton a car i would really like to own, and its the former fastest Vauxhall saloon we have ever had here in Blightly, that was untill Vauxhall start to bring the Monaro replacement in, which incidently is a rebadged Commodore HSV.