Not sure where this thread is going but I am not dusting off the TRS-80 or the Apple IIc.
I have been on both sides of this. The problem with pure simulations is you always end up estimating the effects of components that you don't have sufficient information on to make an accurate model. Good examples are drive train loss, tire grip at launch, shift times, effect of flywheel mass on shifts (next gear lurch), energy wasted as stored rotational energy in the drivetrain (you bleed much of it during shifts), and atmospheric effects.
Unless you have an accurate model for those you are just guessing. The guess are educated based on previous real world result being fed back into the simulation. However as a predictor they are still guesses.