I’m not sure I see this one to be honest. As bad as a car-dense city is for everything else, it’s probably the best option if the whole city had to be evacuated.
A large portion of alternate transport is focused within the city (trams, bikes, subways, etc). I suppose at least busses could be re-purposed for evacuation, but it requires a whole lot more organization.
Run energy changes sound like a good idea. IIRC this is already similar to how RS3 does it; Iwonder when it changed there. Though weight feels like it has no impact in RS3, so that’s probably a good way to balance it.