So what I'm getting at is that there are so many factors that go into figuring out what uniform density box would fit the car, that getting something 100% accurate is almost impossible, because of factors like cars obviously not being a box, different parts of it being heavier than others, ie engine transmission and fuel tank being far heavier than bodywork, as well as things like the roof especially in race cars being vastly ligher than the lower part of the car. at least width should be almost only effected by the inertia being calculated from a complete box.
Side question which I assume it doesn't, but if there's more fuel in the car, does the inertia change on it's own based on where the fuel tank is positioned in car.ini?