Interesting … hmmmm … So are car’s rocker panels curved then? Or do you mean since the term “rocker” applies to the sides of a boat, it would apply to the sides of a car too?
I don’t recall them having much curve on my Corolla. They seem more or less straight, front to back. Maybe the width varies, thicker in the middle possibly. I’d have to crawl underneath the car to say one way or the other. Actually now I think about it I don’t think it is possible to see them, the structural element is covered by a sheet of metal.
I’m thinking the reasoning for the term might be that the rocker panels are analogous to those curved pieces rocking chairs rock on. It’s not just the entire rocking chair that is called a “rocker”. Those curved rails I think are also called “rockers”, and sort of define the foundation of the sides of the rocking chair.
Here’s my theory, what do you think?
Foundation of side of rocking chair == rockers == foundation of side of car?