I have conducted my own (less than scientific I admit) experiment. My commute covers 65 miles and covers most of the A31 to Winchester, the M3, M27 and back onto the A31 at Ringwood.
Armed with only a stopwatch yesterday I aimed to maintain an indicated 80mph on all dual carriageways and motorways. On all roads with a limit of less than 70 I observed the limit.
Today I observed every speed limit including the 70mph, and guess what? My travelling times were both identical 1 hour and 10 minutes.
Once again I contest that no real evidence went into this report.
Mind you since my journey does take me into car hating, revenue raising Dorset I have to observe the ludicrously low 50mph limit on the A31 now! I wonder if since I never saw an accident when it was 70, and since it has been 50 I have seen 3 (obvious tailgating incidents) whether the council will rethink, answers on a post card please
PS I apologise to any pedestrians/cyclists who may have spontaneously combusted etc. as I exceeded the speed limit on a pedestrian/cyclist free motorway. I shall be having stern words with myself for maintaining a minimum 2 second gap at all times I can tell you!