the thing is road rage increases the slower you go.
you allways get some Smeg head in a volvo doing 20mph in a 30, or 40 in a 60, but on the motorway... theres no probs. they all usualy do between 60-80 ish. which is fine as most cars nowadays are easily capable of cruising at 100+mph.
the 70MPH limit came into force what?, 60 years ago?, what cars are available 60 years ago?
what cars are available now? brakes, tyres, engines, gearboxes etc etc are all capable of well exceeding 70mph safely.
i remember when i was younger coming back from Wembly in 1998 (grimsby town won 2-0 by the way) in my uncles lexus LS400, we wanted to catch up to the coaches of fans along the m1, sat at 155mph with 6 people in the car it hardly even felt like it was moving. at all!
but you will stil come accros some gimp doing 35mph in the inside lane..lol