Laugh all you want, but you clearly have no idea what I'm talking about. Ideally, you'd run an exact replica of the entire car, down to every sub-atomic particle. Why don't we? Well, the interesting effects are probably at the macro-molecular level at the lowest (even classical continuum mechanics is a convenient approximation), but that isn't possible to achieve on current hardware either (in real time at least; but it's probably not even explicitly "solvable" at all for many phenomena).
Everything is an approximation, and as a result everything could be better with better hardware, because the approximations can be made with finer strokes, and less of the "real" behaviour can be omitted as a result. You call it an excuse, I call it a fact of life - to get a 1:1 replication, you literally need a 1:1 replication. There will always be room for improvement.
Remember, though, that I was talking primarily about the new sounds. The existing sounds are just "placeholders", as we've been told, and as the new X-cars rather aptly demonstrate.