You do realize that color is not a 3D object, right? The process is completely different of modeling a car, or body part, or whatever. That's why we have a color palette, which alone has literally tousands of shades possible. Did they individually model each tone in the color palette? Plus all the car paints from factory, plus all those special paints (chrome, matte, etc)? Of course not.
Compare that to wheels, which are actual 3D objects, so they go through the same modeling process as a car. In your head, you're thinking "modeling one extra set of wheels, won't consume that many resources", and you're right, it won't, the problem comes when they start adding one extra set of wheel (from the dealership) to many more cars. Let's just say 50 cars get one extra set of wheels, now that would take almost as many resources, as modeling let's say 5 individual cars, or possibly 10 body kits, or updating interiors from GT6 Premium cars. There's a reason why most other games don't do that, and there's no reson for PD to be different, even though some cars have better wheel options that what we end up with in games.
The same applies to the rest of what you want: badges are irrelevant, from a gaming perspective, it makes no difference if the car is called Miata or MX-5, having a mention of the other version in the car description should be enough. As for left or right hand drive, I mean, stating the obvious again, they don't benefit the game in any way, so it's just a pointless way to spend resources (which, once again, could be used to update car interiors from GT6 premiums).