[mindslight]

Alternatively, instead of trying for heavier vehicles with longer hauls, what about something like citywide pizza/package delivery? You've no need for passenger safety, so the size and weight of the vehicle can be brought way down. Speed could also remain relatively low, mitigated by the fact that deliveries could be dispatched immediately rather than aggregating trips. Not that a person getting hit by a 400lb vehicle at 20mph is a laughing experience, but accident damages would be mitigated and an emergency stop-everything would actually be feasible.