A Devil On Wheels

I took a bike ride this afternoon and began thinking about wheels, and how my mother used to reminisce about her mother (my Grandmother Spillard) referring to my mother's cousins -  Marie and Junior - as "Devils on Wheels."  I asked my mother what exactly "Devils on Wheels" were, but she didn't know.  She only knew that Marie and Junior exemplified them.  These days, the older I get, the more I seem to care about family traditions, and this one seems like an ideal tradition to carry on.  I may have to improvise, but I will do my best to keep the "Devil on Wheels" tradition alive.  Someone has to do it, right?