Can I briefly discuss branding of cars?
First off, I think the McLaren F1 GTR from '97 should be listed as a McLaren, rather than a BMW. Sure, it has a BMW engine, but so does the GR Supra. I get the idea that this car is listed as a BMW as a hold-over from GT4, before Gran Turismo was able to formally introduce McLaren into the series.
Second, I have no idea why so many modern Mercedes-AMG cars are listed under AMG rather than Mercedes, despite the latter buying out the former some years ago. I think the Mercedes-Benz and AMG relationship should be similar to Nissan and Nismo; the Nismo 400R is indeed listed as a Nismo model, whereas cars that have been tuned by Nismo after Nissan more fully-integrated them are listed as Nissan models, like the GT-R Nismo. So something like the 300 SEL from 1971 would continue to be listed as an AMG model, as would some of the non-Mercedes models tuned by AMG, like the AMG Galant. I think Mercedes formally created Mercedes-AMG in '99, too, so I think any AMG car from before that should be an AMG.
Or maybe AMG really did transform enough Mercedes vehicles to warrant its own brand in Brand Central. I still hope we get that AMG-tuned Galant, though. That'd be a real curveball. Either way, I suppose I don't get why something like the GT-R Nismo is listed as a Nissan whereas something like the Mercedes-AMG C63 is an AMG.
EDIT: I'm sure there's some relatively complex licensing thing going on here, especially when it comes to official naming of cars. Like it's not called the Nismo GT-R, it's the Nissan GT-R Nismo.