There's no ruse at all. Out of those 33 Miata/MX-5/Roadster models, the only ones that actually existed in real life are the Roadster models. The other 22 are fake; cynical and lazy copy paste jobs by PD to make the car list bigger with no effort put in to make sure that an equivalent model actually existed in the country that the car was sold as a Miata or MX-5. There is no such thing as a Mazda Miata VR-Limited. There is no such thing as a Mazda MX-5 VR Limited. There is a such thing as a Mazda (Eunos) Roadster VR-Limited.
They did the same thing with the Mitsubishi GTO, the same thing with the S2000, the same thing with the RX-7s, the same thing with the Vauxhalls and the same thing with the Renaults. There's even a couple Lexus models where they did it, even though in GT2 they went out of their way to do it properly with that game.
That's nice. It's too bad this has been a known issue ever since GTPSP, though.