When I become Dictator of the Universe Tincow shall be appointed my Czar of Traffic and have a fleet of laser-death-ray-equipped satellites with which to keep traffic moving smoothly.

The fact is the difference in transit times between speeding and doing the limit are so small as to be meaningless. All you "accomplish" is meager self-satisfaction and a false sense of beating time. Save the aggro for something that warrants it; relax and enjoy the drive :p
Going 5-10 mph faster can shorten my commute by 33%.

CR