My 1960's elementary school only taught (drilled) us up to the 10's. I think all of our 11's & 12's time was spent preparing for the imminent move to all-metric.
I was amazed at how true to life many of the drawings were, coming from only verbal Q&A and without any correction/modification from the describe-r. That forensic artist is really, really good.
I know, what is that?! Lacking anything from Google, my very mild guess is that it was maybe related to "tin lizzie" -- maybe a basic car, but especially for paved road?
It really looks as if they just set the guy up with car, camera and toy, and got lucky.