I think your on to something with the "interior" equals "internal" idea.
"170 Premium new models (full interior modeling, the interior corresponds to vehicle damage)"
My guess with this is that there are 170 cars "built" from the ground up. By built, I mean these cars will be very modular in the way they are put together. Where a standard car will have the interior and exterior rendered, these premium cars will go deeper.
I would assume the engine bay would be correctly rendered as so when the hood were to buckle, pop up, or fly off, you would see a correct representation of the engine from that car. Same goes for if the bumper, front or rear, were to fall off. You would need to have an accurate representation of the crash foam and reinforcements that lay behind the bumper cover, or the fender. You get the idea.
If you look at the screenshots from the GT5 Concept Movie, you can see quite clearly that this is probably what they are talking about.
As you can see in the first image, there is quite a lot of detail going on in the engine bay. In the second image, you can make out what looks to be the radiator. As you can see, the headlamps, bumper, fenders, and hood seem to be deformable. It would not surprise me if it were possible for some, if not all, of these parts to fall off the car, revealing the skeleton frame of the car.
Dive into a corner too fast and rear end another car, bumper cover might fall off, revealing the radiator and metal supports behind it. This might not only be cosmetic either, especially if the bumper serves an aerodynamic purpose, which would effect and physical handling of the car. Gives more credence to the damage is visual+physical argument.
You also see that the suspension seems to be very noticeable in these shots. I'm going to go out on a limb and say thats for a reason. I'm thinking this might not go over well with the wall-riders, but I think we're about to see consequences for piloting your car into heavy immovable objects. Could it be possible to see things like knocking the camber or toe out of whack, or even blowing a strut making the car handle horrible? The way the brake caliper, rotor, wheel, and strut look, it almost looks like they're made to be able to separate from the car in the event of a catastrophic impact.
But I'm certain this speak of damage has nothing to do with the "interior" of the car, and like
reece22345 stated, has to do with the internal components and running gear of the car. Why go through all the trouble or rendering things like the suspension if it didn't relate to something important, like damaging the drive-ability of the car?
Hopefully this will all be cleared up soon, because it seems the lack of information is causing a lot of people, gaming blogs and websites included, to completely jump the gun and start building up expectation for things that are not there, or conveying disappointment for features that they don't even fully understand.
But I just thought I'd post my theory on the subject, it's a good topic, and unless Polyphony decides to break their silence, I guess it's up to us to decode
