There used to be an old, old, old text only driving sim called SimuDrive back in the 80s/90s and that would give you the loco you were driving in a random condition performance wise. One drive you might have an ex-works condition loco that accelerated and braked like brand new... Then the next you might have one in well worn condition that took forever to get up to speed and had poorer braking. Is this not something that could be brought into the game these days? Would really add to the skill if you got a poorer performing loco or unit compared to every drive being exactly the same performance wise.