I think that 120 km/hr is definitely fast enough because the majority of studies prove that speed does kill. If some pedestrian crosses the highway, or something falls off a truck, or a car breaks down you can still find yourself in trouble, even if it wasn't related to someone else's bad driving habits.
Basically, if people are courteous, use their lane change signals and plan their route instead of cutting people off or backing up to catch an exit - then the roads would be safer. There are too many selfish people here of all nationalities who think that their trip is more important than someone else's. In the end, selfish and uncivilised driving practices result in slower traffic, more deaths and more injuries.
The police and driving schools could go a long way to solving this problem, but instead they are contributing to the problem, unfortunately.
No matter how beautiful and fun our Murano is, it is a machine for getting us from point a to point b safely - it isn't a toy or a weapon.