This is perhaps the biggest issue against speeding... that you just don't have time if someone else makes a mistake.
I know here on BF I have argued with people that regularly speed, and cite the basic speed law as their justification... while forgetting the laws of physics.
Driving below the speed limit may just give you the opportunity to avoid a situation like this.
BTW, what does this have to do with cycling... everything... we are road users too.