Well the history of speed limits seems to show they were often done for fuel conservation reasons rather than safety reasons.
Agree about public transport. lthough I fear it wont get better, because its already pretty near capacity in many places, and I struggle to imagine it coping well with the increase in passengers that the future requires.
A friend who drives tells me that a lot of the speed limits round here have been reduced by the local authorities, so maybe even if a new national limit is not imposed, the trend is still there.