The numbers that made an impression on me was someone telling me that if someone walks out in front of a parked bus at the same instant you start to pass it, if you're doing a legal and nominally sensible 30mph you wont even have touched the brakes when you run into them. I was skeptical till I did the sums; yep, he was right!
People go on about "better brakes" on cars, but our reflexes haven't improved a jot, and are likely worse in practical terms as there are now far more distractions, both from traffic and stupid crap within the cars