Roads outside of cities: flat and level, even if the stones themselves are broken down somewhat.
City elves could have a bonus for running along these. Why not? They resemble the flat and level alleys and roads and streets they're used to. There just aren't any walls around.
EDIT: it might generate some plot pressure to keep the old roads in repair too.
EDIT 2: Is this already the case? Usually there are ten people telling me why it shouldn't be so by now.
I don't know, specifically, about the running portion.
I know I had a city elf in Luir's that I would take out along North Road pretty regularly. Would require a rest at the span, but could make the 'run' to Morin's pretty successfully.
I don't have logs so I don't remember if he was running the whole way or not.