[giantg2]

Don't some of the higher powered cars in Japan have a GPS system that won't allow them to exceed certain street limits?

Places that have some roads with unrestricted speed probably wouldn't be a candidate for non-GPS blanket restrictions (Germany has the autobahn, Montana has/had some roads posted as 'reasonable speed').

There is also the argument against both types of restrictions that some situations can warrant excess speeds. If you are speeding to a hospital because your neighbor has potentially life threatening injuries from being run over by a tractor, most states have a clause that allows you to break the laws to avoid greater harm in situations like this.

The best answer I know of so far is to increase driver test requirements in the US. Many European countries have more stringent testing with lower fatalities per million miles, even when comparing US interstates to the German autobahn. The number of drivers I witness who make bad decisions or don't know the law is quite high.