There are a variety of racing cars that either are from Japan or raced there, that that I'd like to see make it into GT7 (or GT8, whenever that comes out)
Toyota 88-CV
The famous "Minolta", one of the icons of GT4, being one of the fastest Group C cars in that game. While I doubt it will be quite as good in modern GT, with the franchises focus on more realistic vehicle performance, it still is an iconic piece of GT history and with Toyota having somewhat recently given the car a full once over restoration, it would be cool to see the Minolta re-appear in the GT franchise, now with a detailed cockpit for PSVR users to drool over.
HKS Mercedes CLK GT500
An obscure pick, but none-the-less awseome is this attempt by the HKS Tuning company to tackle the top class of JGTC with a home-built weapon, that sadly never truly got up to speed, and was shortly dropped. Despite a lackluster IRL performance, an appearance in Gran Turismo would certainly give it a second lease on life, especially for those who want something different for GT500 races.
JLOC Lamborghini Diablo JGT-1
Another JGTC also-ran is the iconic NOMAD Diablo, that notably snuck into the Japanese release of GT3 via licensing loophole. While my preference is the older GT-1 spec Diablo, I'd gladly take either, and it would be cool if you could boost the power to match GR.2 machinery, as a reference to the original intended destination for the Diablo in Europe.
Toyota 7
Another GT Hood Classic is Toyota's lethal weapon that unfortunately met that descriptor in more ways than one. While on one hand, the history of the car would likely give Toyota some pause in seeing it return, that didn't stop it form appearing in GT4-6, so who knows?
Nissan 382
Now a car that has never appeared in a GT game is the car Toyota explicitly developed the Seven to beat, and that is the all conquering 382, a part of a lineage of Japanese excellence that had a stranglehold on Japanese sports car racing throughout the late 60's. While the 383 would likely be a more direct match for the Seven, the fact it never raced likely diminishes it's chances compared to it's more successful fore-bearer.
SARD MC-8
What happens when you take an MR2, stretch the body, and drop in a 4-Liter V8 powering the rear wheels? You get the MC8, a one of one prototype developed by Toyota's Sigma Advanced Research Development Team to run at LeMans. The main reason I have chosen the road car over the racing version is due to the fact that AFAIK the racing version is sitting in a field without drivetrain, while the road going homologation model still prowls the streets of Japan under private ownership. And with GT7's visual customization system, a replica of the race car should be possible anyways.
Nissan R390 GT1
I've mentioned this car before, but I'll bring it up again, as of the GT1 cars in GT7, this is one of the big missing pieces, and the last holdout of the GT3's "Big 3" race cars, alongside the 787B and GT-One. It's only a matter of time before this beast makes it's Gran Turismo return, and I'd bet when it does, the community will go absolutely nuts.
Nissan Fairlady Z GT4
Going modern with this next choice, everyone knows the roster of modern race cars in GT7 is a bit "lacking," and with Nissan's latest challenger, why not add the Z GT4 into GT7, or at least a fictional GR.4 variant.
Nissan Z GT300
Or, if PD won't add a Group 4 Nissan Z, why not add a sparing partner to the Subaru BRZ that currently stands at the only piece of GT300 representation in GT7 (which is dumb, considering that GT has always had some selection of GT300 machines since the days of GT2)
And finally to add a track to GT7, I'd split this into 2 segments, 1 real track, 1 returning GT original.
Autumn Ring: GT Original
- Autumn Ring is the remaining non Special-Stage location from the original Gran Turismo games not in the current iteration of the GT franchise, and while the focus on the past tracks have been real world locations, Autumn Ring is such a classic that I'd love to see it back (even if PD will likely screw it up, hopefully they don't give it the Grand Valley treatment.)
Mobility Resort Motegi: Real World
- Another track with GT history, and one rumored in active development, Motegi would bring a lot to GT7, having both a Road Course that would go well with the Super Formula and Super GT cars on display, but also an oval track, that while not hosting any major races recently, is still in usable condition as of current writing, and despite GT7 already having a few ovals in Daytona, Blue Moon, Broad Bean, and Northern Isle, I wouldn't turn down another option.