100km/hr is much too slow a limit on modern freeways with modern cars. I agree Bundy that speed limits have not moved with the times. The NT used to have no speed limit on highways but recently introduced a limit of 130 km/hr. Since then I have read accidents have increased in part due to drivers falling asleep at the wheel due to longer travel times.
Speed alone never killed anyone, bad drivers sometimes going to fast for prevailing conditions are the killers.