Thank you for the enlightenment everyone. Much appreciated

Because it helps keep us straight for phases when Corsas could be either Vauxhall or Opel - it's easier to have all Corsas of the same underlying generation with the same numbering, rather than out of step. Putting Mk1 on Novas is useful as a marker that something's going on, and hopefully deters folk from inventing Nova Mk2s.

The other issue when pondering Carltons, Rekords, Omegas etc is that we have a system which everyone is used to. If we change established practice (a) it'll usually generate hiccups and (b) it should be to bring actual improvement. "Different" does not necessarily mean "better" in these scenarios.

Thanks ^ then why does the Nova all have mk1 ?

And the Vauxhall Corsa B has mk2?

Indeed, even if it matches the second generation of Opel Omega, it is not a second generation Vauxhall Omega, there is no need to differentiate it from something else with the same name.
In the same way, you won't put mk2 on the Cadillac Catera I suppose

There's no need for a Mk for the Vauxhall Omega, there was only one generation. Same with the Nova. The Belmont (sedan version of the Astra Mk2) was also only one generation and as such doesn't have a Mk field either.

In addition, it doesn't make any sense to call the Vauxhall Omega the Mk2 as the preceding Omega [A] is the Vauxhall Carlton Mk3. The Vauxhall Carlton Mk1 and Mk2 are known as the Opel Rekord E1 and E2.

antp do you care/anyone else if I start adding MK2 to the Vauxhall Omega? Right now they do not have any MK.

For the smaller Vauxhall Nova/Opel Corsa A we have all the Nova listed as MK1. Then the Vauxhall/Opel Corsa B we have MK2 repectively.

I am going to go through them and wanted to ask before I just start changing the way we list them and if antp could possibly wave his wand and add MK2 to all of them to make it easier

One that I did manually but wanted to note here:

"The 2013 Chevrolet TrailBlazer was designed at GM’s South America Design Center in São Caetano do Sul, Brazil, and it will be built at the automaker’s Thailand manufacturing facility in Rayong."

Built on the GMT31XX platform.

https://www.cars.com/articles/first-look-2013-chevrolet-trailblazer-1420663127420/

So these should be "Origin: Brazil", unified all the codes to GMT31XX, and the name uses a lower-case "b".

Here's a press release from Chevrolet:
https://media.cadillac.com/media/me/en/chevrolet/vehicles/2013/2013-trailblazer/2013.html

done

2017-2022 Nissan Rogue Sports and Canadian Qashqais [J11] were made in Japan. North American models were made in the factory in Fukuoka. And there are a few listed with origin: Japan, which should be Europe.

I'm going to do the Canadian ones manually, since there are only a few of them.

https://imcdb.org/search.php?resultsStyle=asList&sortBy=0&make=Nissan&model=Rogu- e+Sport

Thanks. I'll try to find more info to see if I can improve any IDs, particularly non-years.