But the chances of survival being hit at 38mph are significantly lower than at 30, or even 33.

I've been knocked down by a car doing 5mph. My head was embedded in the bonnet, bounced off it, and then I was on the road staring at the underside and tyre of a fortunately stopped car before my puny human brain could figure out what happened.

Being hit, even at 5mph, is not something you'd want, let alone 38.