I don’t know if anyone has already mentioned this, but for those who are fans of the GT franchise’s gameplay and who learned to appreciate Super GT cars through it, it’s frustrating to see how PD has given virtually no attention to the new and old cars from the Japanese championship, while Project Motor Racing is out there releasing an absolutely fantastic car pack featuring them.
I think the 2024 GT500 trio would be perfect, as it'd be a 100% turnover in models from the 2016 trio, and the idea of a Honda Civic with an FR drivetrain and over 500 HP sounds very interesting indeed! I'd also say that unlike previous GT games, GT Sport and onwards seems to have a more "careful" selection of cars, especially racecars that might fit into the same group. (Personally, I like this approach better, versus having identical cars from the same season of the same series, with their liveries being the only main difference.) That being said, I still think there are more Super GT/JGTC cars that'd be great fits beyond the obvious 2024 GT500 trio, especially when it comes to GT300. For example, the Lexus LC500 GT300 from the 2023 season would be a splendid friend to the Subaru BRZ GT300 from the 2021 season. Plus, with Lexus' GT3 effort being effectively unknown with the introduction of the GR GT3, the LC500 GT300 would make for a newer Lexus Gr.3 racer, replacing the nearly decade-old RC F GT3.
As for more historic Super GT/JGTC racers go, I think the most important ones have been covered with the turn-of-the-millennium JGTC GT500 trio, but that said, I still see an opening for more, especially ones
not from the "big three" Japanese automakers. Even in the context of Super GT/JGTC cars that've
already appeared in Gran Turismo, there's potential to see racers like the Mitsubishi FTO GT300 '99, the RE-Amemiya RX-7 '06, or the Autobacs Garaiya GT300 '08.
EDIT: Some of those JGTC GT300 racers could even make for interesting Gr.4 picks, like the aforementioned Mitsubishi FTO GT300, as it was FF.
EDIT2: On another note regarding racecars, I wonder what automaker could become eligible for the Manufacturers Cup next? My bet is actually Maserati. Given their motorsport heritage, I could see the MC20 GT2 and a Gr.4 version of the newer GranTurismo being their picks. I could see a made-for-game Gr.3 version of the MC20/MCPura being an alternative to the MC20 GT2, but then again, if the Toyota GT-One (TS020) ended up in Gr.2 despite having 150 more horsepower than the 2016 GT500 trio and even out-powering some of the Group C racers in Gr.1, then I don't see why BoP wouldn't be able to jam the MC20 GT2 into Gr.3.
EDIT3: I did read the that MC20 GT2 has about 621HP, so if it were added with that figure in particular, the MC20 GT2 would be the 2nd most-powerful Gr.3 racer, more or less being right between the Dodge Viper GT3-R and the AMG GT3 '20. That said, the MC20 GT2 would also be the heaviest Gr.3 racer, at around 1475 kgs/3252 lbs, whereas the SLS-AMG GT3 is 1350 kgs/2976 lbs.
EDIT4: And furthermore, the MC20 GT2 has a power/weight ratio of about 2.37 kgs/HP, which would give it one of the lower power/weight ratios and placing it right between the Toyota FT-1 VGT Gr.3 (2.35 kg/HP) and the Honda NSX GT500 '00 (2.39 kg/HP). Of course, this is all before BoP is factored in.