Less crashes on our motorways than other roads. Very true.
However, if involved in a motorway crash you are far more likely to be critically injured or killed...
Simple reason, speed.
The question is, where do you draw the line? If the limit were 150mph there would still be people that feel the need to get to where they are going at 180mph.
There is no definitive "safe speed" for a motorway or any road but if you want less fatalities the lower the limit the better.
Personally, seeing how some drivers can't even park a car properly, 70mph is fine by me.
Am i prefect,no? Have I ever broken speed limits, yes?
In my youth I was an idiot. At 49 I stick to the limits to the best of my ability only going over slightly due to "speed creep" as you simply can't keep your eye on the speedo all the time.
Personally I think that 100mph+ on a motorways should be a mandatory ban, no ifs, no buts.
Also, just to check, this is a biking forum isn't it? Motorways not withstanding we are some of the most likely to get injured/killed by a reckless driver. Whether that recklessness is speeding or negligence the result can be the same.