"Velocity Change and Fatality Risk in a Crash–A Rule of Thumb" by Joksch. When collisions result in a Delta-V of 65mph, collisions are on the order of 70% fatal.
The fitted curve predicts the fatality rate to be ((delta-v / 71) ^ 4), suggesting a 100% death rate at 71mph.
Dropping down to 65mph drops your fatalities to 70%. Dropping down another 5mph to 60mph drops you to 50% fatality rate. The 5mph after that is a 36% chance of fatality.
So the 65mph limit is a rather magical number in terms of surviving a worst-case scenario. Going above that, fatalities go up dramatically. Going below that... fatalities are significantly lower.
The fitted curve predicts the fatality rate to be ((delta-v / 71) ^ 4), suggesting a 100% death rate at 71mph.
Dropping down to 65mph drops your fatalities to 70%. Dropping down another 5mph to 60mph drops you to 50% fatality rate. The 5mph after that is a 36% chance of fatality.
So the 65mph limit is a rather magical number in terms of surviving a worst-case scenario. Going above that, fatalities go up dramatically. Going below that... fatalities are significantly lower.