A good deal of this has already been shared by Mazda on Twitter, but in trying to replicate the 12R decals, I came across this press release by Mazda with 122 photos of PD scanning the car.
マツダ株式会社(以下、マツダ)は、PlayStation®5、PlayStation®4用ソフトウェア「グランツーリスモ7」*1に「MAZDA SPIRIT RACING ROADSTER 12R(マツダ スピリットレーシング ロードスター
newsroom.mazda.com
According to the article itself, it was Mazda who approached PD to include the 12R, not the other way around!
The process of scanning and recording the car is immensely cool to see. The photos also show wireframe models of the 12R. Unless PD deliberately hid them, it doesn't look like the engine bay or boot is scanned. If we are to assume that models being scanned now are considered future–proof, I think this means we won't get opening parts anytime soon in the GT franchise. Shame.
Also, I am incredibly annoyed that the 12R's tow hook still drills through the tow hook covers instead of, you know... removing the covers.
And let's not forget this thing costs as much as a freaking 2013 Viper for some ungodly reason. According to Mazda Spirit Racing representative Maeda Ikuo,
the 12R is projected to cost around 7 Million Yen (47,050USD in with today's conversion). Feels like PD just saw the "12" in the name and went hurr 120,000Cr. Honestly, the car's price might drop once upgrades are unlocked for it and the car is finalised.
I can also confirm the 12R in the game currently has 200PS and weighs 1,050kg (147kW, 2.315lbs) by setting lobby restrictions and seeing if the car can enter. So dumb of PD to obscure basic stats when such a simple workaround exists...